ee6301 digital logic circuits unit i boolean algebra...
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EE6301 – DIGITAL LOGIC CIRCUITS
UNIT I – BOOLEAN ALGEBRA AND COMINATIONAL CIRCUITS
PART A
1. How can an OR gate be realized using NAND gates? (M-13)
2. Define – Multiplexer (M-13)
A multiplexer is a digital switch which allows digital information from several
sources to be routed into a single output line. The basic multiplexer has several data
input lines and a single data output line. The selection of a particular input line is
controlled by a set of selection lines. Normally there are 2n input lines and n
selection lines.
3. What is meant by priority encoder? (M-12)
A priority encoder is an encoder that includes the priority function. The
operation of the priority encoder is such that if two or more inputs are equal to 1 at
the same time, the input having the highest priority will take precedence.
Inputs Outputs
D0 D1 D2 D3 Y0 Y1 V
0 0 0 0 X X 1
1 0 0 0 0 0 0
X 1 0 0 0 1 0
X X 1 0 1 0 0
X X X 1 1 1 0
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4. Distinguish between decoder and demultiplexer. (N-11)
5. State De-Morgan’s theorem. (A-11)
De - Morgan suggested two theorems that form an important part of
Boolean algebra.
They are,
1) The complement of a product is equal to the sum of the complements.
= +
2) The complement of a sum term is equal to the product of the
complements.
=
6. Draw the truth table and logic circuit of half adder. (A-10)
Inputs Outputs
A B Sum (S) Carry (C)
0 0 0 0
0 1 1 0
1 0 1 0
1 1 0 1
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7. What is meant by decoder? (M-09)
A decoder is a combinational circuit that decodes the binary information on „n‟
input lines to a maximum of 2n unique output lines. The general structure of
decoder circuit is
8. What is meant by encoder? (M-10)
An encoder is a combinational circuit that converts binary information from 2n
input lines to a maximum of „n‟ unique output lines. The general structure of
encoder circuit is
9. List out the applications of multiplexers. (M-09)
1. Data routing
2. Logic function generator
3. Control sequencer
4. Parallel-to-serial converter.
10. What is meant by demultiplexer? (M-08)
A demultiplexer is a combinational logic circuit with an input line, 2n output
lines and n select lines. It routes the information present on the input line to any of
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the output lines. The output line that gets the information present on the input line is
decided by the bit status of the selection lines.
UNIT II –SYNCHRONOUS SEQUENTIAL CIRCUITS
PART A
1. Define – Flip Flop (M-13)
Flip flop is defined as the basic unit for storage. A flip-flop maintains its output
state either at 1 or 0 until directed by an input signal to change its state.
2. What is meant by race around condition? (N-12)
In JK flip-flop output is fed back to the input. Therefore change in the
output results leads to change in the input. Due to this, in the positive half of the
clock pulse if both J and K are high then output toggles continuously. This
condition is called race around condition‟.
3. Compare combinational circuits with sequential circuits.
S. No. Combinational circuits Sequential circuits
1. Memory unit is not required Memory unity is required
2. Parallel adder is a combinational circuit Serial adder is a sequential circuit
4. What are the various classifications of sequential circuits? (N-11)
The sequential circuits are classified on the basis of timing of their signals into two
types. They are as follows:
1) Synchronous sequential circuit
2) Asynchronous sequential circuit
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5. What is the operation of D flip-flop? (M-11)
In D flip-flop during the occurrence of clock pulse if D=1, the output Q is set
and if D=0, the output is reset.
6. What is meant by master-slave flip-flop? (M-10)
A master-slave flip-flop consists of two flip-flops where one circuit serves as a
master and the other as a slave.
7. Write the excitation tables for a JK flip-flop. (N-09)
In JK flip-flop there are four possible transitions from the present state to the
next state. They are as follows:,
_ 0_0 transition: This can happen when J=0 and K=1 or K=0.
_ 0_1 transition: This can happen either when J=1 and K=0 or when J=K=1.
_ 1_0 transition: This can happen either when J=0 and K=1 or when J=K=1.
_ 1_1 transition: This can happen when K=0 and J=0 or J=1.
8. Compare synchronous counters with asynchronous counters. (M-10)
9. What is meant by edge-triggered flip-flop? (M-09)
The problem of race around condition can be solved by edge triggering flip flop.
The term edge triggering means that the flip-flop changes state either at the positive
edge or negative edge of the clock pulse and it is sensitive to its inputs only at this
transition of the clock.
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10. What are the different types of flip-flop?
There are various types of flip flops. They are as follows:
1) RS flip-flop
2) SR flip-flop
3) D flip-flop
4) JK flip-flop
5) T flip-flop
UNIT III – ASYNCHRONOUS SEQUENCITIAL CIRCUIT
1. What is meant by race condition in an asynchronous sequential circuit?
A race condition is said to exist in an asynchronous sequential circuit when
two or more binary state variables changed value in response to a change in an input
variable. The order by which the state variables change may not be known in
advance if the final stable state that the circuit reaches does not depend on the order
in which the state variable changes. The race is called a non-critical race.
2. What are called hazards?
Hazards are unwanted switching transients that may appear at the output of a
circuit because different paths exhibit different propagation delays.
The 3 types of hazards are
1. Static hazards
Static – 0 hazards
Static – 1 hazard
2. Dynamic hazards
3. Essential hazards
3. What are the assumptions made for fundamental mode circuit?
The assumptions made for fundamental mode circuit are
1. The input variables change only when the circuit is stable
2. Only one input variable can change at a given time
3. Inputs are levels and not pulses
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4. Define – Flow Table in an asynchronous sequential circuit
During the design of asynchronous sequential circuits, it is more convenient to
name the states by letter symbols without making specific reference to their binary
values. Such a table is called a flow table.
5. What are the steps to be followed in the designing of a asynchronous sequential
circuit?
The steps to be followed in the design of asynchronous sequential circuit are
1. Construction of a primitive flow table from the problem statement
2. Primitive flow table is reduced by eliminating redundant states using the
state reduction
3. State assignment is made
4. The primitive flow table is realized using appropriate logic elements
6. Define – Static 0-Hazard, Static 1-Hazard and Dynamic Hazard (A-09)
Static-1 hazard: In a combinational circuit, if output goes momentarily 0 when
it should remain a1, the hazard is known as static-1 hazard.
Static-0 hazard: In a combinational circuit, If the output goes momentarily 1
when it should remain a 0, the hazard is known as static-0 hazard.
Dynamic hazard: When the output changes three or more times when it should
change from 1 to 0 or from 0 to 1, it is known as dynamic hazard.
7. What is meant by critical race? Why should it be avoided?
Race exists in synchronous sequential circuits when two or more binary state
variables charge during a state transition. A race becomes critical if the correct next
value is not reached during a state transition. For the proper operation of the
circuits, the critical races must be avoided.
8. What is meant by cycle?
A cycle occurs when an asynchronous circuit makes a transition through a series
of unstable states. If a cycle does not contain a stable state, the circuit will go from
one unstable to stable, until the inputs are changed.
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9. How does an essential hazard occur? (A-12)
An essential hazard occurs due to unequal delays along two or more paths that
originate from the same input. An excessive delay through an inverter circuit in
comparison to the delay associated with the feedback path causes essential hazard.
10. What are the significances of state assignment?
In synchronous circuits-state assignments are made with the objective of circuit
reduction. In asynchronous circuits its objective is to avoid critical races.
UNIT IV PROGRAMMABLE LOGIC DEVICES, MEMORY AND
LOGIC FAMILIES
1. Explain ROM. (N/D-12)
A read only memory (ROM) is a device that includes both the decoder and the
OR gates within a single IC package. It consists of n input lines and m output lines.
Each bit combination of the input variables is called an address. Each bit
combination that comes out of the output lines is called a word. The number of
distinct addresses possible with n input variables is 2n.
2. What are the various types of ROM? (M/J-11)
1. Masked ROM
2. Programmable Read only Memory
3. Erasable Programmable Read only memory
4. Electrically Erasable Programmable Read only Memory
3. What is meant by programmable logic array? How does it differ from ROM?
In some cases the number of don‟t care conditions is excessive. It is more
economical to use a second type of LSI component called a PLA. A PLA is similar
to a ROM in concept. However it does not provide full decoding of the variables
and does not generate all the min-terms as in the ROM.
4. What is meant by CPLD?
CPLDs are Complex Programmable Logic Devices. They are larger versions of
PLDs with a centralized internal interconnect matrix used to connect the device
macro cells together.
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5. Define – Cache Memory (M/J-13)
It is a relatively small, high-speed memory that can store the most recently used
instructions or data from larger but slower main memory.
6. Compare PROM with PLA.
PROM PLA
1. AND array is fixed and OR Both AND and OR arrays are
array is programmable. programmable.
2. Cheaper and simple to use. Costliest and more complex
than PROMS
7. List out the classifications of a saturated bipolar logic families.
The bipolar logic family is classified as follows:
1. RTL- Resistor Transistor Logic
2. DTL- Diode Transistor logic
3. I2L- Integrated Injection Logic
4. TTL- Transistor Transistor Logic
5. ECL- Emitter Coupled Logic
8. Define – Fan-out
Fan out specifies the number of standard loads that the output of the gate can
drive With out impairment of its normal operation.
9. Define – Noise Margin
It is the maximum noise voltage added to an input signal of a digital circuit that
does not cause an undesirable change in the circuit output. It is expressed in volts. .
10. How are Schottky transistors formed?
A schottky diode is formed by the combination of metal and semiconductor.
The presence of schottky diode between the base and the collector prevents the
transistor from going into saturation. The resulting transistor is called schottky
transistor. The use of Schottky transistor in TTL decreases the propagation delay
without a sacrifice of power dissipation
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UNIT V –VHDL
PART A
1. What is meant by Verilog? (N/D-12)
Verilog is a general purpose hardware descriptor language. It is similar in
syntax to the C programming language. It can be used to model a digital system at
many levels of abstraction ranging from the algorithmic level to the switch level.
2. What is meant by switch-level modeling? (M/J-10)
Verilog allows switch-level modeling that is based on the behavior of
MOSFETs. Digital circuits at the MOS-transistor level are described using the
MOSFET switches.
3. What are called value sets in verilog? (N/D-11)
Verilog supports four levels for the values needed to describe hardware referred
to as value sets.
Value levels Condition in hardware circuits
0- Logic zero, false condition
1 -Logic one, true condition
X -Unknown logic value
Z -High impedance, floating state
4. List out the various classifications of timing control. (M/J-11)
The various classifications of timing control are as follows:
1. Delay-based timing control
2. Event-based timing control
3. Level-sensitive timing control
Types of delay-based timing control:
1. Regular delay control
2. Intra-assignment delay control
3. Zero delay control
Types of event-based timing control:
1. Regular event control
2. Named event control
3. Event OR control
4. Level-sensitive timing control
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5. What are the various types of conditional statements? (M/J-12)
The types of conditional statements are as follows:
1. No else statement
Syntax: if ([expression]) true – statement;
2. One else statement
Syntax: if ([expression]) true – statement;
else false-statement;
3. Nested if-else-if
Syntax : if ( [expression1] ) true statement 1;
else if ( [expression2] ) true-statement 2;
else if ( [expression3] ) true-statement 3;
else default-statement;
The [expression] is evaluated. If it is true (1 or a non-zero value) true-
statement is executed. If it is false (zero) or ambiguous (x), the false-statement is
executed.
6. What are the various types of ports in verilog? (N/D-13)
The various types of ports in verilog are as follows:
Types of port Keyword
Input port Input
Output port Output
Bidirectional port In out
7. What are the various modeling used in verilog? (M/J-09)
The various modeling used in verilog are as follows:
1. Gate-level modeling
2. Data-flow modeling
3. Switch-level modeling
4. Behavioral modeling
8. What is meant by structural gate-level modeling? (M/J-11)
Structural modeling describes a digital logic network in terms of the
components that make up the system. Gate-level modeling is based on using
primitive logic gates and specifying how they are wired together.
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9. What are called gate primitives? (N/D-12)
Verilog supports basic logic gates as predefined primitives. Primitive logic
function keyword provides the basics for structural modeling at gate level. These
primitives are instantiated like modules except that they are predefined in verilog
and do not need a module definition. The important operations are and, nand, or,
xor, xnor, and buf (non-inverting drive buffer).
10. What are the various types of procedural assignments? (M/J-13)
The various types of procedural assignments are as follows:
1. Blocking assignment
2. Non-blocking assignment
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EE6302 ELCTROMAGNETIC THEORY
UNIT – I – ELECTROSTATICS – I
1. Define – Scalar and Vector
Scalar: Scalar is defined as a quantity that is characterized only by magnitude.
Vector: Vector is defined as a quantity that is characterized both by magnitude and
direction.
2. Define – Scalar Multiplication of two vectors
Scalar multiplication of two vectors is defined as a scalar quantity whose
magnitude is the product of the magnitudes of the vectors multiplied by the cosine of
the angle between them. It is referred as dot product.
A . B = ABcosθ
3. Define – Vector Multiplication of two vectors
The vector product of two vectors is defined as a vector whose magnitude is
the product of the magnitudes of the two vectors and the sine of the angle between
them. This multiplication is called “Cross Product”.
A x B = ABsinθ
4. Show that the two vectors A = 6 a x + a y -5 a z and B = 3( a x + a y - a z) are
perpendicular to each other.
For perpendicular dot, product of two vectors should be zero.
0.BA
A =6 a x + a y -5 a z
B =3( a x + a y - a z)
A . B = 6 x 5 – 2 x 5 – 5 x 4
= 0
AVector and B are perpendicular to each other.
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5. Show that the two vectors A =4 a x -2 a y +2 a z and B =-6 a x +3 a y -3 a z are parallel
to each other.
For parallel 0BXA
A =4 a x -2 a y +2 a z
B =-6 a x +3 a y -3 a z
A x B =
336
224
zyx aaa
= a x(6-6) - a y(-6+6) + a z(12-12)
= 0
Vectors A and B are parallel to each other.
6. Define – Gradient of any scalar function
The gradient of any scalar function is defined as the maximum space rate of change
of that function. If the scalar V represents electric potential, V represents potential
gradient.
V= x
Vxa +
y
Vya +
z
Vza
This operation is called the gradient.
7. Define – Divergence of a vector
The divergence of a vector „A‟ at any point is defined as the limit of its surface
integrated per unit volume, as the volume enclosed by the surface shrinks to zero.
.A =Lt 0V v
1
SA . n ds.
.A = x
AX +y
AY +z
AZ
This operation is called divergence. Divergence of a vector is a scalar quantity.
8. Define – Curl of a vector
The curl of a vector „A‟ at any point is defined as the limit of its cross product with
normal over a closed surface per unit volume as the volume shrinks to zero.
x A =Lt 0V v
1
Sn x Ads.
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9. Show that the vector H = 3y4z a x + 4x
3z
2a y +2 x
3y
2 a z is solenoidal.
For solenoidal 0.H
.H= x
xa +y
ya +z
za . (3y4z a x + 4x
3z
2a y +2 x
3y
2a z
)
= x
(3y4z)+
y( 4x
3z
2)+
z( 2 x
3y
2)
= 0 + 0 + 0 = 0
Hence H is solenoidal.
10. Find the dot products of the vectors A and B if A = zyx aaa 432 and
zyx aaaB 22
A.B =AxBx+AyBy+AzBz
= 2(-1)-3(2) +4(2)
= 0
11. Given A= zy aa 84 and zy aaB 62 find A . B
A.B = AxBx +AyBy +AzBz
= 4(-2) + 8(6)
=40
12. Write the expression for conversion of Cartesian to Cylindrical system.
The Cartesian co-ordinates (x, y, z) can be converted into cylindrical co-ordinates (r,
Φ, z).
Given Transform
x r = 22 yx
y Φ = tan-1
(y/x)
z z = z
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13. Write the expression for conversion of Cylindrical to Cartesian system.
The Cylindrical co-ordinates (r, Φ, z) can be converted into Cartesian co-
ordinates (x, y, z).
Given Transform
r x = r cosθ
Φ y = r sinθ
z z = z
14. Write the expression for conversion of Cartesian to Spherical system.
The Cartesian co-ordinates ( x, y, z ) can be converted into spherical co-ordinates (r,
θ, Φ).
Given Transform
x r = 222 zyx
y θ =cos-1
(222 zyx
z)
z Φ = tan-1
(y/x)
15. Write the expression for conversion of spherical to Cartesian system.
The spherical co-ordinates (r, θ, Φ) can be converted into Cartesian co-ordinates (x,
y, z).
Given Transform
r x = rsinθ.cosΦ
θ y = r sinθ.sin Φ
Φ z = rcosθ
16. Transform the Cartesian co-ordinates x = 2, y = 1 and z = 3 into Spherical
co-ordinates.
Given Transform
x = 2 r = 222 zyx = 914 = 3.74
y = 1 θ =cos-1
(222 zyx
z) = cos-1(
14
3) = 36.7
z = 3 Φ = tan-1
(y/x) = tan-1
(1/2) = 26.56
The spherical co-ordinates = (3.74, 36.7 , 26.56 ).
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17. Write the Cartesian co-ordinates of a point whose Cylindrical co-ordinates are r
= 1, Φ =45 , z=2.
Given Transform
r = 1 x = r cosθ = 1.cos45 = 0.707
Φ =45 y = r sinθ = 1.sin45 = 0.707
z = 2 z = z = 2
The Cartesian co-ordinates = (0.707, 0.707 , 2)
18. State Divergence theorem.
The volume integral of the divergence of a vector field over a volume is equal to the
surface integral of the normal component of this vector over the surface bounding the
volume.
v
AdV. = S
dSA.
19. State Stoke’s Theorem.
The line integral of a vector around a closed path is equal to the surface integral of
the normal component of its equal, to the integral of the normal component of its curl
over any closed surface.
dlH. =S
xHdS
20. Express the value of differential volume in rectangular and cylindrical
co-ordinates systems.
For rectangular co-ordinate
dv = dxdydz
For cyclindrical co-ordinate
dv = rdrdθdz.
21. Write the expression for differential length in cylindrical and spherical
co-ordinates.
For cylindrical co-ordinates
dl = 222 )()()( dzrddr
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For spherical co-ordinates
dl = 222 )sin()()( drrddr
22. Define – Unit Vector
A unit vector in a given direction is defined as a direction in that direction divided
by its magnitude.
(or)
A unit vector is having unit magnitude and directed along the co-ordinate axes.
ar = r
r
23. Find the distance from A (1, 2, 3) to B (2,0,-1) in rectangular co-ordinates.
r = 2
12
2
12
2
12 )()()( zzyyxx
= 222
1 )31()20()12(
= 1641
= 21
24. What is the divergence of curl of a vector?
0. HX
25. Fill up the blanks ____________xAx
AAxAx2
.
26. What is the physical significance of divergence of D ?
The divergence of the vector flux density D is the outflow from a small closed
surface per unit volume as the volume shrinks to zero.
D. = v
dsDLTv
.
0
27. Express the divergence of a vector in the three systems of orthogonal
co-ordination.
For rectangular co-ordinate system
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B. = z
Bz
y
By
x
Bx
For cylindrical co-ordinate system
B. =r
1
z
BzB
rr
rBr 1)(
For spherical co-ordinate system
B. =sin
12r
(rBBr
rr
Brr )sin(1)sin( 2
)
28. Show that the two vectors A = 6xa + ya - 5 za and B = 3(
xa - ya + za ) are
perpendicular to each other.
A . B = (6x3) + (1x-3) + (-5x-3)
= 18-3-15
= 0
UNIT – II – ELECTROSTATICS II
1. Define – Electric Flux and Electric Flux Density
Electric Flux:
Electric flux is defined as the lines of electric force. It is denoted by .
= Q (charge) Coulomb.
Electric Flux Density:
Electric flux density or displacement density is defined as the electric flux per unit
area.
D = A
Q
2. State the point form of Gauss’s law.
The divergence of electric flux density is equal to the volume charge density.
D. ρv.
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3. State Coulomb’s law.
Coulomb‟s law states that the force between two very small charged objects
separated by a large distance compared to their size is proportional to the charge on each
object and inversely proportional to the square of the distance between them.
F Q1Q2
F2
1
r
F2
Q1Q2
r
F = 1224
Q1Q2a
r Newton.
4. Write the applications of Gauss’s law in electrostatics.
Gauss‟s law is applied to determine the electric field intensity from a closed
surface.
( e.g) Electric field can be determined for shell, two concentric shells or
cylinders, etc.
5. What is meant by point charge?
Point charge is one whose maximum dimension is very small in comparison with
any other length.
6. What is meant by linear, surface and volume charge densities?
Linear Charge density: It is the charge per unit length ( Col / m) at a point on the line
of charge.
ρl = Lt 0l (l
Q)
Surface charge density: It is the charge per surface area ( C/m2) at a point on the
surface of the charge.
ρs = Lt 0s (s
Q )
Volume charge density: It is the charge per volume ( C/m3) at a point on the volume
of the charge.
ρs = Lt 0v (v
Q )
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7. Define – Electric Field Intensity or Electric Field
Electric field intensity is defined as the electric force per unit positive charge. It is
denoted by E.
E = Q
F
E = 24 r
Q
8. Define – Potential and Potential Difference
Potential: Potential at any point is defined as the work done in moving a unit positive
charge from infinity to that point in an electric field.
V = r
Q
4 Volts.
Potential Difference: Potential difference is defined as the work done in moving a
unit positive charge from one point in an electric field.
V = 4
Q(
BA rr
11) Volts.
9. What is the relation between intensity of electric field E and electric flux density D
in free space?
D = εE c/m2
Where
ε – Permittivity of the medium, ε = ε oεr
10. Write the relationship between potential gradient and electric field.
E = V
E = -x
xa +y
ya +z
za v
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11. What is the electric field intensity at a distance of 20 cm from a charge of 2 μc in
vacuum?
E = 24 r
Q
=212
6
)2.0(10854.84
102
xxx
x
=04.0
1092 3xx = 450 KV/m.
12. Find the electric potential at a point (4, 3) m due to a charge of 10-9
C located at
the origin in free space.
V =r
Q
O4
r = 22 34 = 5m.
V =)5(1210854.84
910
xxx = 1.8V
13. What is the physical significance of divD?
D. ρv
The divergence of a vector flux density is electric flux per unit volume leaving a
small volume. This is equal to the volume charge density.
14. Write the Poisson’s equation and Laplace equation.
Poission equation
V2 ρ/ε
where
ρ – Volume charge density
ε – Permittivity of the medium
2 - Laplacian operator.
2
2
x
V+
2
2
Y
V+
2
2
z
V= - ρ/ε
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Laplace equation
02V
2
2
x
V+
2
2
Y
V+
2
2
z
V=0
15. Represent in unit vector along a vector R =6xa +8
ya
Unit Vector Ra =R
R=
6436
a8+ a6 yx
= 100
a8+ a6 yx
= 10
a8+ a6 yx
= 0.6 xa +0.8ya
16. A uniform line charge, infinite in extent, with ρl = 20nc/m lines along the z axis.
Find E at (6, 8, 3) m.
r = 222 386
= 96436
= 109
E = ρl / 2πεor = 10910854.82
102012
9
xxx
x = 34.48 V/m
17. State the condition for the vector F to irrotational.
The vector F is said to be irrotational if FX = 0
18. Define – Dipole and Dipole Moment
Dipole or electric dipole is defined as two equal and opposite point charges
separated by a very small distance.
The product of electric charge and distance ( spacing) is known as dipole moment.
It is denoted by m where Q is the charge and l is the length.
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m = Q. l C/m
19. Define – Capacitor
A capacitor is defined as a device which consists of two conductors separated by a
dielectric medium.
20. Define – Capacitance
The capacitance of two conducting planes is defined as the ratio of magnitude of
charge on either of the conductors to the potential difference between conductors. It is
given by
V
QC
The unit of capacitance is coulomb / volt or Farad.
21. Determine the capacitance of a parallel plate capacitor with two metal plates of
size 30cm x 30cm separated by 5mm in air medium.
Given data,
A = 0.3 X0.3 = 0.09m2
d =5 x 10-3
m.
` εo = 8.854 x 10-2
C = 2
A εo
= 3105
10854.809.0 12
X
XX= 15.9 nf
22. Write the expression for the value of capacitance for a co-axial cable.
C =
a
bro
ln
2
where
b – outer radius.
a – inner radius.
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23. Write the expression for the energy density in electro static field.
2
2
1E
v
W
= DE2
1
24. Find the energy stored in a parallel plate capacitor of 0.5m by 1m if it has a
separation of 2cm and a voltage difference of 10V.
C = εo d
A
= 2
12
102
15.010854.8
x
xxx
= 2.2135x10-10
F
Energy stored in a capacitor
E = 1/2 CV2
= 1/2 X 2.2135 X 10-10
X102
= 1.10675 X 10-8
Joules.
25. Write down the expression for the capacitance between two co-axial cylinders.
C =
a
do
ln
where
d – distance between two transmission lines in m
a – radius of cylinders in m
26. State the boundary conditions at the interface between two perfect dielectrics.
a) The tangential component of electric field E is continuous at the surface. That E is
the same just outside the surface as it is just inside the surface.
Et1 = Et2
b) The normal component of electric flux density is continuous if there is no surface
charge density. Otherwise D is discontinuous by an amount equal to the surface charge
density.
Dn1 = Dn2
65
27. A parallel plate capacitor has a charge of 10-3
C on each plate while the potential
difference between the plates is 1000V.Calculate the value of capacitance.
Given data,
Q = 10-3
C
V = 1000V
To find C,
C = V
Q
C = 3
3
10
10 = 1μF
28. State point form of Ohm’s law.
Point form of Ohm‟s law states that the field strength within a conductor is
proportional to the current density.
J E
J = ζE
where
ζ is conductivity of the material.
29. What is meant by conduction current?
Conduction current is nothing but the current flowing through the conductor.
Conduction current density is given by
Jc = ζE Amp / m2
30. What is meant by displacement current density?
Displacement current is nothing but the current flowing through the capacitor.
Displacement current density is given by,
Jd = t
D Amp / m
2
31. Define – Polarization in Dielectric Material
Polarization in dielectric material is defined as a dipole moment per unit volume.
P= Lt 0vv
1 vn
i
iP1
66
UNIT – III – MAGNETOSTAICS
1. Define – Magnetic Flux
Magnetic flux is defined as the flux passing through any area. Its unit is Weber .
a
daB. Wb
2. Define – Magnetic Flux Density
Magnetic flux density is defined as the magnetic flux density passing per unit area.
Its unit is Weber / meter or Tesla.
B = A
B = μH
3. Define – Magnetic Gauss’s Law
The total magnetic flux passing thorough any closed surface is equal to zero.
a
daB 0.
4. State Biot- Savart law .
It states that the magnetic flux density at any point due to current element is
proportional to the current element and sine of the angle between the elemental length
and the line joining and inversely proportional to the square of the distance between
them.
24
sin
r
IdldB o
5. Write the force on a current element.
The force on a current element Idl is given by
dF = I x B dl
= BI dl sinθ Newton.
6. State the Lorentz force equation.
The force on a moving particle due to combined electric and magnetic field is given
by
F = Q BxVE
This force is called Lorentz force.
67
7. State Ampere’s circuital law.
Ampere‟s circuital law states that the line integral of magnetic field intensity H
about any closed path is exactly equal to the direct current enclosed by the path.
IdlH.
8. What is field due to toroid and solenoid?
a) Toroid r
NIH
2
b) Solenoid l
IH
9. Write down the expression for magnetic field at the centre of the circular coil
a
IH
2
10. Define – Scalar Magnetic Potential
It is defined as dead quantity whose negative gradient gives the magnitude intensity
if there is no current source present.
mVH
where Vm is the magnetic scalar potential.
dlHVm .
11. Define – Magnetic Vector Potential
Magnetic vector potential is defined as that quantity whose curl gives the magnetic
flux density
B x A
where A is the magnetic vector potential.
drr
JA
V4
Web / m
68
12. Distinguish among diamagnetic, paramagnetic and ferromagnetic materials.
Diamagnetic : In diamagnetic materials magnetization is opposed to the applied field.
It has magnetic field.
Paramagnetic: In paramagnetic materials magnetization is in the same direction as the
field. It has a weak magnetic field.
Ferromagnetic : In Ferromagnetic materials magnetization is in the same direction as
the field. It has strong magnetic field.
13. A solenoid with a radius of 2 cm is wound with 20 turns per cm length and carries
10 mA. Find H at the centre if the total length is10 cm.
Given data,
N=nl = 20 x 10 = 200 turns.
l =10 X 10-2
m
I = 10 x 10-3
A
l
NIH
= 2
3
1010
1010200
x
xx
= 20AT/m.
14. Define – Mechanical Moment
The tangential force multiplied by the radial distance at which it acts is called
torque or mechanical moment on the loop.
15. Define – magnetic moment
The magnetic moment is defined as the maximum torque on loop per unit magnetic
induction (Flux density).
m = IA
where
A is Area.
69
16. Write the force on a current element.
The force on a current element Idl is given by
dF = I x Bdl
= BI dl sinθ
17. Write the torque on closed circuits.
The torque on closed circuit in a magnetic field is
T = BIA cosθ
T = mBcosθ
where
m is magnetic moment
In vector form T = m x B
18. Write the expression for torque on a solenoid.
Torque on a solenoid in a magnetic field is
T = 2
n. 2IAB
= nBIA
= mB
where
m = nIA
19. Compare electrostatic field with magnetic field.
Electrostatic field Magnetic field
Electric field intensity E ( volts/m )
Electric flux density D=εE c/m
Energy stored is 1/2CV2
Charges are at rest
Magnetic field intensity H ( Amp/m )
Magnetic flux density B=μH (web /
m2)
Energy stored is 1/2LI2
Charges are in motion
70
20. Determine the force per unit length between two long parallel wires separated by 5
cm in air and carrying currents 40A in the same direction.
Force per unit length between two long parallel wires is
Force / length = D
IIo
2
21
=2
7
1052
4040104
XX
XXX
=6.4 x 10-3
N/m
21. Define - Magnetic Dipole
A small bar magnet with pole strength Q m and length l may be treated as magnetic
dipole whose magnetic moment is Q ml.
22. Define - Magnetization
Magnetization is defined as the ratio of magnetic dipole moment to unit volume.
M = Volume
oleMagnticdip ; M = a
A
Qm A/m
23. Define – Magnetic Susceptibility
Magnetic susceptibility is defined as the ratio of magnetization to the magnetic field
intensity. It is dimensionless quantity.
H
Mm
24. What is the relation between relative permeability and susceptibility?
mr 1
where
r is relative permeability
m is susceptibility
25. What are the different types of magnetic materials?
The magnetic materials can be classified into three groups according to their
behavior. They are diamagnetic, paramagnetic and ferromagnetic materials.
71
26. Write the magnetic boundary conditions.
1. The tangential component of magnetic field intensity is continuous across the
boundary.
Ht1 = Ht2
2. The normal component of magnetic flux density is continuous across the boundary.
Bn1 = Bn2
27. Define – Self Inductance
The self induction of a coil is defined as the ratio of total magnetic flux linkage in
the circuit to the current through the coil.
L = i
N
where
is magnetic flux
N is number of turns of coil
i is the current.
28. Define – Mutual Inductance
The mutual inductance between two coils is defined as the ratio of induced
magnetic flux linkage in one coil to the current through in other coil.
M = 1
122
i
N
where
N2 is number of turns in coil 2
12 is magnetic flux links in coil 2
i1 is the current through coil 1
29. Define – Co-efficient of Coupling
Co-efficient of coupling is defined as the fraction of the total flux produced by one
coil linking the second coil (K).
K = 1
12 = 2
21
where
1 is the flux produced by coil 1
72
12 is flux links coil 2
K 1
K = 21LL
M
30. What will be the effective inductance, if two inductors are connected in (a) series
and (b) parallel?
(a) For series L = L1 + L2 M2 + sign for aiding
(b) For Parallel L = MLL
MLL
221
2
21 - sign for opposition
31. Write the expression for inductance of a solenoid.
l
ANL o
2
where
N is number of turns
A is area of cross-section
l is length of solenoid
o is free space permeability.
32. Write the expression for inductance of a toroid.
R
ANL o
2
2
=R
rNo
2
22
where
N is number of turns
r is radius of the coil
R is radius of toroid
o is free space permeability.
73
33. Write the expression for inductance per unit length of a co-axial transmission
line.
L = a
bo ln2
H/m.
Where
a is the radius of inner conductor
b is the radius of outer conductor.
34. Distinguish between solenoid and toroid.
Solenoid: Solenoid is a cylindrically shaped coil consisting of a large number of
closely spaced turns of insulated wire wound usually on a non – magnetic frame.
Toroid: If a long, slender solenoid is bent into the form of a ring and thereby closed on
itself, it becomes toroid.
35. What is the mutual inductance of two inductively tightly coupled coils with self
inductance of 25 mH and 100 mH.
L1 = 25 mH.
L2 = 100 mH
M = K 21LL
= 10025 X
= 50 mH
UNIT – IV – ELECTRO DYNAMIC FIELDS
1. State Faraday’s law of electromagnetic induction.
Faraday‟s law states that electromagnetic force induced in a circuit is proportional
to the rate of change of magnetic flux linking the circuit.
emf = Ndt
d
2. Define – Magneto Motive Force
Magneto motive force (mmf ) is defined as the product of magnetic flux and
reluctance of that magnetic circuit.
mmf = flux x reluctance
mmf = Φ AT
74
3. Define – Reluctance
Reluctance is defined as the ratio of mmf of magnetic circuit to the flux through it.
)(flux
mmf
It is also written as
A
l
where
l is the length in m
A is the area of cross- section in m2
μ is permeability
μ = μ0 μr
μ0 = 4π x 10-7
H / m
4. In a solenoid with an inductance of 5 mH, current is increasing at the rate of 100
A/sec. What is the value of induced emf?
Solution:
Given
L = 5 mH = 5 x 10-3
H
di / dt = 10 A / sec
Formula Used
emf = dt
diL
= 5x10-3
x 100 = 0.5V
5. Write the expression for lifting force of an electro magnet.
F = o
AB
2
2
where
B is flux density
A is area of air gap between the poles of the magnet
o is permeability of free space
μ0 = 4π x 10-7
H / m
75
6. What is the expression for energy stored in magnetic field?
W = 2
2
1LI Joules
Where
L is the inductance in Henry
I is the current in Amp
7. What is energy density in the magnetic field?
Energy density w = BH2
1
= 2
2
1H
where
B – Magnetic flux density in wb / m2
H – Magnetic field intensity in H / m
μ is permeability
μ = μ0 μr
μ0 = 4π x 10-7
H / m
8. Write down the general, integral and point form of Faraday’s law.
emf dt
dv ( General )
dst
BdlE. ( Integral )
t
BE ( Point form )
9. Distinguish between transformer emf and motional emf.
The emf induced in a stationary conductor due to the change in flux linked
with it, is called transformer emf or static induced emf.
emf = - dst
B. eg. Transformer.
The emf induced due to the movement of conductor in a magnetic field is called
motional emf or dynamic induced emf.
emf =-c
dlBv . eg. Generator
76
10. State Lenz’s law.
Lenz‟s law states that the induced emf in a circuit produces a current which opposes
the change in magnetic flux producing it.
11. State Dot rule.
If both the currents enter dotted ends of coupled coils or if the both currents enter
undotted ends, then the sign on the M will be same as the sign on the L.
If one current enters a dotted end and the other an undotted end, the sign on the M
will be opposite to the sign on the L.
12. Compare electric circuit with magnetic circuit.
Electric circuit Magnetic circuit
1. emf (volts)
2. Current =ceresis
emf
tan
3. Resistance R = A
l
4. Conductance G = R
1
mmf ( Amp-turns )
Magnetic flux = cereluc
mmf
tan
Reluctance A
l
Permeance P =1
13. A region in free space has a magnetic field intensity of B web/m2. What is the
energy stored per m3
of space?
Energy density = Energy per volume
=2
2
1 B Joules / m
3
where,
μ – is the permeability of the medium; B – Magnetic flux density in wb / m2
77
14. Write the Maxwell’s equation in integral form.
From Ampere‟s Law
dst
DJdlH
S
.
From Faraday‟s Law
dst
BdlE
S
.
From Electric Gauss‟s Law
vs
dvdsD.
From Magnetic Gauss‟s Law
0.s
dsB
15. Write the Maxwell’s equation in point form.
From Ampere‟s Law
t
DJH
From Faraday‟s Law
t
BE
From Electric Gauss‟s Law
D.
From Magnetic Gauss‟s Law
0.B
16. Write the fundamental postulate for electromagnetic induction and explain how
its leads to Faraday’s Law.
A changing magnetic flux (Φ) through a closed loop produces an emf or voltage at
the terminals as given by
dt
dv
where the voltage is the integral of the electric field E around the loop.
78
For uniform magnetic field Φ = B/A where B is the magnetic flux density and A is the
area of the loop.
dst
BdlEv .
This is Faraday‟s law. It states that the line integral of the electric field around a
stationary loop equals the surface integral of the time rate of change of the magnetic
flux density B integrated over the loop area.
17. What is the significance of displacement current? Write the Maxwell’s equation in
which it is used.
The displacement current iD through a specified surface is obtained by integration
of the normal component of JD over the surface.
iD = S
D dsJ .
= dst
D
S
.
iD = dst
E
This is a current which directly passes through the capacitor.
Maxwell‟s equation
DC JJHX
= t
EE (Differential form )
dst
DJdlH
SC
)(. (Integral form )
18. Find the total current in a circular conductor of radius 4mm if the current density
varies according to J = 24
/10
mAr
.
Solution:
J = 24
/10
mAr
Current I = dsJ.
79
= rdrdr
r
.10
004.0
0
42
0
= dr
004.0
0
2
0
410
= 10-4
. 0.004 . 2
0
= 80π
19. Write Maxwell’s equations in point phasor forms.
EjDjJHX )(
HjBjEX
D.
0.B
20. Write Maxwell’s equations in integral phasor form.
SS
dsEjdsDjJdlH .)()(.
SS
dsHjBdsjdlE ..
dvdsDS
.
0.S
dsB
21. Write Maxwell’s equation in integral form.
From Ampere‟s Law
dst
DdlH
S
.
From Faraday‟s Law
dst
BdlE
S
.
From Electric Gauss‟s Law
80
0.s
dsD
From Magnetic Gauss‟s Law
0.s
dsB
22. Write Maxwell’s equation in point form.
From Ampere‟s Law
t
DH
From Faraday‟s Law
t
BE
From Electric Gauss‟s Law
0.D
From Magnetic Gauss‟s Law
0.B
23. Explain why 0.B
0.B states that there are no magnetic charges. The net magnetic flux emerging
through any closed surface is zero.
24. Explain why .0EX
In a region in which there is no time changing magnetic flux, the voltage around the
loop would be zero.
By Maxwell‟s equation
t
BE =0
25. Explain why 0.D
In a free space there is no charge enclosed by the medium . The volume charge
density is zero.
By Maxwell‟s equation
0. vD
81
26. Compare circuit theory with field theory.
Circuit Theory Field Theory
1. This analysis originated by its own. Evolved from Transmission theory.
2. Applicable only for portion of RF range. Beyond RF range ( Microwave )
3. The dependent and independent
parameters I, V are directly obtained for the
given circuit.
Not directly , through E and H.
4. Parameters of medium are not involved. Parameter of medium ( permittivity and
permeability) are involved in the
analysis.
5. Laplace Transform is employed. Maxwell‟s equation is employed
6. Z, Y, and H parameters are used . S parameter is used.
7. Low power is involved. Relatively high power is involved.
8. Simple to understand. Needs visualization ability
9. Two dimensional analysis Three dimensional analysis
10.Frequency is used as reference. Wave length is used as reference
11. Lumped components are involved Distributed components are involved.
82
UNIT – V
ELECTROMAGNETIC WAVES
1. What is meant by wave?
If a physical phenomenon that occurs at one place at a given time is reproduced at
other places at later times, the time delay being proportional to the space separation
from the first location, then the group of phenomenon constitutes a wave.
2. List out the properties of uniform plane wave.
The properties of uniform plane wave are as follows
1. At every point in space, the electric field E and Magnetic field H are
perpendicular to each other and to the direction of the travel.
2. The fields vary harmonically with the time and at the same frequency,
everywhere in space.
3. Each field has the same direction, magnitude and phase at every point in any
plane perpendicular to the direction of wave travel.
3. Write the wave equations for E and H in a non-dissipative ( free space ) medium.
02
22
t
EE oo
02
22
t
HH oo
4. Write the wave equations for E and H in a conducting medium.
02
22
t
E
t
EE
02
22
t
H
t
HH
5. Define – Plane Wave
The plane wave is defined as the phase of a wave that is the same for all points on a
plane surface.
83
6. Define – Uniform Plane Wave
Uniform plane wave is defined as the phase of a wave that is the same for all points
on a plane surface it is called plane wave. If the amplitude is also constant in a plane
wave, it is called uniform plane wave.
7. What are the properties of uniform plane waves?
1. At every point space electric field (E) and magnetic field (H) are perpendicular
to each other and to the direction of travel.
2. The fields vary harmonically with time and at the same frequency, everywhere
in space.
3. Each field has the same direction, magnitudes and phase at every point in any
plane perpendicular to the direction of wave travel.
8. Define – Intrinsic Impedance or Characteristic Impedance
Intrinsic impedance is defined as the ratio of electric field to magnetic field.
Otherwise it is the ratio of square root of permeability to permittivity of the medium.
H
E
9. Calculate intrinsic impedance or characteristic impedance of free space.
o
o
H
E
=12
7
10854.8
104
x
x= 120π = 377 ohms
10. Write the expression for propagation constant.
The propagation constant (γ) is a complex number and it is given by
j
where
α is attenuation constant
β is phase constant
jj (
84
11. Define – Skin Depth or Depth of Penetration
Skin depth or depth of penetration (δ) is defined as the depth in which the wave has
been attenuated to 1 / e (or approximately 37% of its original value).
21
for good conductor.
12. Define – Polarization
Polarization is defined as the polarization of a uniform plane wave refers to the time
varying nature of the electric field vector at some fixed point in space.
13. What is meant by linear polarization?
If x and y component of electric field Ex and Ey are present and are in phase, the
resultant electric field has a direction at an angle of tan-1
(X
Y
E
E) and if this angle is
constant with time, the wave is said to be linearly polarized.
14. What is meant by circular polarization?
If x and y component of electric field Ex and Ey have equal amplitude and 90o
phase difference, the locus of the resultant electric field E is an circle and the wave is said
to be circularly polarized.
15. What is meant by Elliptical polarization?
If x and y component of electric field Ex and Ey have different amplitude and 90o
phase difference, the locus of the resultant electric field E is a ellipse and the wave is
said to be elliptically polarized.
16. Find the skin depth at a frequency of 2 MHz is Aluminum where σ = 38.2 M s/m
and μr = 1.
Solution:
Given data
ζ = 38.2M s/m = 38.2 x 106 s/m
μr = 1
610222 xxf
85
For Good conductor,
Skin depth
21
=676 102.38.1041.102.2
2
xxxx
= 5.758 x 10-5
m.
17. At what frequencies may earth be considered perfect, if σ = 6 x 10-3
s/m, μr = 1 and
εr = 10.
1
This is the boundary line between dielectric and conductor 1
110108
2
01109366
10854.8.
106 63
12
3
f
x
f
xxx
x
X
f = 108 x 106 Hz
if frequency is greater than 108MHz , it acts as dielectric.
18. A uniform plane wave in free space is described by E = 100e-(πz/3) xa
. Determine
the frequency and wave length.
E=100 e
-(πz/3) xa
Β = 2
=3
m6
MHzxe
f 506
103 8
19. Write Helmholtz’s equation.
022 EE
where
)( jj
86
20. Define – Pointing Vector
Pointing vector is defined as rate of flow of energy of a wave as it propagates. It is
the vector product of electric field and magnetic field.
P = E x H
21. Write the expression for average power flow in electromagnetic field and average
pointing vector.
Average power
Wav = COSIV
2
Average Pointing vector
Pav = 1 / 2Real part of [ E x H* ]
22. Write the complex Pointing vector in rectangular co-ordinates.
Px = ½ [ Ey Hz* - EzHy* ]
23. Define – Slepian Vector
Slepian vector is defined as a vector which defines at every point such that its flux
coming out of any volume is zero. 0).( S . Slepian vector is given by
)( HxS
where,
V is electric potential
H is magnetic field intensity
24. State Pointing theorem.
The vector product of electric field intensity at any point is a measure of the rate of
energy flow per unit area at that point.
P = E x H
25. State Snell’s law.
When a wave is travelling from one medium to another medium, the angle of
incidence is related to angle of reflection as follows.
1
2
2
1
sin
sin
t
i ( )021
87
where
i is angle of incidence
t is angle of refraction
1 is dielectric constant of medium 1
2 is dielectric constant of medium 2
26. What is meant by Brewster angle?
Brewster angle is an incident angle at which there is no reflect wave for parallely
polarized wave.
1
21tan
where
1 is dielectric constant of medium 1
2 is dielectric constant of medium 2
27. Define – Surface Impedance
Surface impedance is defined as the ratio of tangential component of electric field at
the surface of a conductor to the linear current density.
sJ
EZs tan
where
is propagation constant
is conductivity medium
28. Write the expression for plane electromagnetic waves propagating in a dielectric
media in a direction x with respect to origin ( 0, 0 , 0)
The equation for plane electromagnetic waves propagating in a dielectric medium is
given by
2
2
2
21
x
E
t
E yy
(or)
2
2
2
21
x
H
t
H yy
88
29. In a time varying situation how is a good conductor and lossy dielectric defined?
For good conductor
>>1
f2
α and β are large i.e., the wave is attenuated greatly as it propagates through the
conductor.
For lossy dielectric, dielectric current becomes complex,
'''
<<1
2
and
Loss tangent of the medium is defined as
'
''tan
30. What is meant by total internal reflection?
When a wave is incident from the denser medium to rarer medium at an angle equal
to or greater than the critical angle, the wave will be totally internally reflected back.
This phenomenon is called total internal reflection.
31. Write the expression for pointing theorem in point form.
Pointing theorem in point form is given by
][2
1. 222 EH
tEP
32. Write the expression for pointing theorem in integral form.
The expression for pointing theorem in integral form is given by
VVS
EHtt
EdsP ][2
1. 222
89
33. What is normal incidence and oblique incidence?
Normal incidence:
When a uniform plane wave incidences normally to the boundary between the
media, then it is known as normal incidence.
Oblique incidence:
When a uniform plane wave incidences obliquely to the boundary between the two
media, then it is known as oblique incidence.
34. Define – Standing Wave Ratio
Standing wave ratio is defined as the ratio of maximum to minimum amplitudes of
voltage.
S =1
1
min1
max1
s
s
E
E
90
GE6351 / GE2021 ENVIRONMENTAL SCIENCE AND ENGINEERING
UNIT-I
ENVIRONMENT, ECOSYSTEMS AND BIODIVERSITY
PART – A
1. What is meant by ecology?
Ecology is study of interactions among organisms or group of organisms with
their environment.
2. What is meant by ecosystem?
A group of organisms interacting among themselves and with environment.
3. List various types of ecosystem.
Forest ecosystem, grassland ecosystem, desert ecosystem and lake ecosystem.
4. List out the structural components of ecosystem.
The structural components of ecosystem are
1) Biotic components
2) Abiotic components
5. What is meant by primary production?
The conversion of radiant energy into organic substances during
photosynthesis by the primary producers.
6. List out the characteristics of desert ecosystem.
1) The desert air is dry and the climate is hot
2) Annual rain fall is less than 25cm.
3) Vegetation is poor.
91
7. Distinguish between food chain and food web.
Food chain Food web
The sequence of eating and being
eaten in an ecosystem.
The interlocking pattern of various food
chains in an ecosystem.
8. What is meant by food web?
The interlocking pattern of various food chains in an ecosystem is known as
food web.
9. What is meant by food chain?
The sequence of eating and being eaten in an ecosystem is known as food
chains.
10. What is meant by ecological pyramid?
The graphical representation of structures and functions of tropic levels of an
ecosystem.
11. State the significance of ecological pyramid.
In ecological pyramid, producer level forms the base and successive levels
form tiers which make up the apex.
12. What is meant by tropic level?
The various steps through which food energy passes in an ecosystem is called
tropic level.
13. What is meant by water cycle?
The movement of water in a cyclic manner is known as water cycle.
14. What is meant by biogeochemical cycle?
The cyclic flow of nutrients between the biotic and abiotic components is
known as biogeochemical cycle.
15. What is meant by ecological succession?
Ecological succession is the progressive replacement of one community by
another till the development of stable community in a particular area.
92
16. List out the types of ecological succession.
1) Primary succession
2) Secondary succession
17. What is meant by biodiversity?
The variety and variability among all groups of living organisms and the
ecosystem in which they occur.
18. State the necessity to conserve biodiversity.
It is necessary to conserve biodiversity to preserve the genetic diversity of
plants and animals.
19. What is meant by ecosystem diversity?
The diversity at the ecological or habitat level is known as ecosystem
diversity.
20. What is meant by hotspots of biodiversity?
The hotspots are geographic areas which posses the high endemic species.
21. List out the reasons to justify India as a great spot of biodiversity.
India is one among the 12 mega diversity countries in the world. It has
89,450 animal species accounting for 7.31% of the faunal species and 47,000 plant
species which accounts for 10.8% of the world floral species.
22. State the threats to biodiversity.
A species is said to be threatened, when its number has been reduced to a
critical level.
23. Distinguish between biodiversity and ecosystem biodiversity.
Biodiversity Ecosystem biodiversity
The variety and variability among all
groups of living organisms.
The diversity at the ecological or
habitat level.
24. What is meant by endemism?
The species, which are found only in a particular region are known as
endemism.
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25. What is meant by endangered species?
A species is said to be endangered, when its number has been reduced to a
critical level.
26. List out the aesthetic values of biodiversity.
The aesthetic values of biodiversity are eco tourism (colour of butterfly,
music of wild birds, colour of flowers, and colour of peacocks).
27. State any two methods to conserve biodiversity.
In-situ and Ex-situ are the two methods to conserve biodiversity.
28. State the bio geographical classification of India.
Himalayan mountain, desert, semi arid, Western Ghats and genetic plain.
UNIT-II
ENVIRONMENTAL POLLUTION
1. What is meant by pollution?
The unfavorable alteration of our surrounding is called pollution.
2. State the types of pollutants.
The types of pollutants are:
1) Biodegradable
2) Non-degradable
3. What is meant by acid rain?
Rain water with excessive acid is known as acid rain.
4. List out the sources of air pollution.
The sources of air pollution are:
Fossil fuel, smoking, vehicles and industries
5. What is meant by suspended particulate matter?
Suspended particulate matter is a combination of variety of particles and
droplets which can suspend in air for lesser or longer duration.
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6. What is meant by photochemical smog?
The brownish smoke like appearance that is frequently formed on clear,
sunny days over large cities with significant amount of automobile traffic. It is mainly
due to chemical reactions among nitrogen oxides and hydrocarbon by sunlight.
7. How does air pollution controlled?
The air pollution can be controlled as followed:
1) Use only unleaded petrol.
2) Use petroleum products and other fuels that have low sulphur and ash
content.
8. What is meant by automobile pollution?
The emission of particulate matters, gases like CO2 during
the combustion of fuels from vehicles.
9. List out the water pollutants.
The water pollutants are pesticides, industrial and agricultural
wastes and heavy metals.
10. What is meant by point and non-point sources?
Point sources are discharged pollutants at specific location through pipes,
ditches or Sewers into bodies of surface water.
Non point sources cannot be traced to any single site of discharge. They are
usually large land areas or air sheds that pollute water by runoff, subsurface flow or
deposition from the atmosphere.
11. What is meant by bioaccumulation?
Bioaccumulation is the accumulation of dead plants and animals in soil.
12. What is meant by BOD and COD?
BOD is the amount of dissolved oxygen required for biological
decomposition of organic matter present in the water.
COD is the amount of oxygen required for chemical oxidation of organic
matter using some oxidising agents like K2Cr2O7 and KMnO4.
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13. List the sources of soil pollution.
The sources of soil pollution are industrial wastes, urban wastes, agricultural
practice and radioactive pollutants.
14. List the causes of soil pollution.
The causes of soil pollution are industrial wastes, urban wastes, agricultural
practice and radioactive pollutants.
15. What is meant by soil pollution?
The contamination of soil by human and natural activities which may cause
harmful effects on living beings is known as soil pollution.
16. What is meant by aerobic and anaerobic oxidation?
The oxidation takes place in presence of air is known as aerobic oxidation
and in absence of air is known as anaerobic oxidation.
17. State the sources of marine pollution.
The sources of marine pollution are dumping the wastes and oil.
18. List out the effects of noise pollution.
The effects of noise pollution are:
1) It causes muscles to contract leading to nervous breakdown, tension etc.,
2) It affects human health, comfort and efficiency.
19. State the control methods of thermal pollution.
The control methods of thermal pollution are cooling towers, cooling ponds,
spray ponds and artificial lakes.
20. What is meant by thermal pollution?
Thermal pollution is the addition of excess of undesirable heat to water that
makes it harmful to man, animal or aquatic life or otherwise causes significant
departures from the normal activities of aquatic communities in water.
21. State the damages caused by nuclear radiations.
Radioactive radiation affects the cells in the body and the function of glands
and organs.
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22. State the two radio isotopes used in nuclear fission reactions.
U235
and Radon-222
23. What is meant by domestic sewage?
The garbage material which is thrown out from the homes is known as
domestic sewage.
Example: food waste, waste cloth, waste paper
24. List the types of solid wastes.
The types of solid wastes are:
1) Urban or Municipal wastes
2) Industrial wastes
3) Hazardous wastes
25. What is meant by hazardous wastes?
Hazardous wastes are the wastes that pose a substantial danger immediately
or over a period of time to human, plant or animal life.
26. List out the role of an individual in reducing pollution.
The role of an individual in reducing pollution:
1) Plant more trees
2) Use water, energy and other resources efficiently
3) Reduce deforestation
4) Use CFC free refrigerators
27. List out the various types of natural disasters.
The various types of natural disasters are:
1) Cyclone
2) Earthquake
3) Floods
4) Tsunami
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UNIT-III
NATURAL RESOURCES
1. What is meant by environmental studies?
Environmental studies are the process of educating the people for preserving
quality environment.
2. State the principles of environmental education.
Environmental education is the application of engineering principles to the
protection and enhancement of the quality of the environment and protection of
public health and welfare.
3. State the scope and importance of environmental studies.
The scopes of environmental studies are:
1) To get an awareness and sensitivity to the total environment and its related
problems.
2) To motivate the active participation in environmental production and
improvement.
The importances of environmental studies are:
1) Environmental studies have a direct relation to the quality of life we live.
2) Environmental studies develop a concern and respect for the environment
4. State the need for public awareness for solving environmental problems.
The need for public awareness for solving environmental problems are:
1) In law making process
2) Controlling pollution activities
5. List out the major causes of deforestation.
The major causes of deforestation are:
1) Developmental projects
2) Mining operations
3)Shifting cultivation
4) Forest fires
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6. List out two uses of forest resources.
The uses of forest resources are:
1) Production of oxygen
2) Reducing global warming, soil conservation and pollution moderators
7. What is meant by overgrazing?
Overgrazing is a process of eating away the forest vegetation without giving
it a chance to regenerate.
8. What is meant by mining?
Mining is the process of extraction of metals from a mineral deposit.
9. List out the types of mining.
The types of mining are:
1) Surface mining
2) Underground mining
10. List out the uses of dams.
The uses of dams are:
1) To control flood and store flood water
2) Dams are built for generating electricity
11. What is meant by soil erosion?
Soil erosion is the process of removal of superficial layer of the soil from one
place to another.
12. What is upstream impact of dam construction?
The upstream impacts of dam construction are:
1) Displacement of tribal people
2) Loss of forests, flora and fauna
13. Enumerate the effects of mining on the environment.
The effects of mining on the environment are:
1) Mining reduces the shape and size of the forest areas
2) Noise pollution
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14. What is meant by eutrophication?
Eutrophication is a large proportion of N and P fertilizers used in crop fields
which are washed off by the runoff water and reaches the water bodies causing over
nourishment of the lakes.
15. What is meant by water logging?
Water logging is the land where water stand or stagnate for most of the year.
16. What is meant by salinization?
Salinization is the process of accumulation of salts in the soil.
17. State any two problems due to the over exploitation of ground water.
The over exploitation of ground water are:
1) Decreases the level of ground water
2) Ground subsidence
3) Earthquakes and land slides
18. What is meant by an aquifer?
Aquifer is a layer of highly permeable rock containing water.
19. State the effects of ground water usage.
The effects of ground water usage are:
1) Intrusion of salt water
2) Lowering of water table
3) Drying up of wells
20. List out the types of minerals.
The types of minerals are:
1) Metallic minerals
2) Non Metallic minerals
21. State the uses of minerals.
The uses of minerals are:
1) Development of industrial plants and machinery
2) Making of alloys for various purposes
3) Generation of energy
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22. List out any two methods of flood control.
The methods of flood control are:
1) Floods can be controlled by constructing dams and reservoirs
2) Encroachment of flood ways should be banned
23. State the types of drought.
The types of drought are:
1) Metrological drought
2) Hydrological drought
3) Agricultural drought
4) Socio-economic drought
24. What is meant by soil leaching technique?
Soil leaching technique is the process in which materials in the soil
gradually dissolve and are carried by water seeping through the soil.
25. State the environmental effects of extracting mineral resources.
The environmental effects of extracting mineral resources are:
1) Ground water contamination
2) Air, soil and water pollution
3) Devegetation and subsidence of land
26. State the advantages and disadvantages of modern agriculture.
The advantages of modern agriculture are:
1) Good crop yield
2) High tech techniques
The disadvantages of modern agriculture are:
1) Micronutrient imbalance
2) Water logging
27. What is meant by under nutrition?
Under nutrition means due to poverty the people cannot buy their basic
needs and they receive less than 90% of these minimum dietary calories.
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28. Distinguish between organic and synthetic fertilizers.
S. No. Organic fertilizers Synthetic fertilizers
1 Natural fertilizers Man-made fertilizers
2 Eco friendly Non-Eco friendly
29. State any three damages caused by fertilizers.
The damages caused by fertilizers are:
1) Micronutrient imbalance
2) Blue baby syndrome
3) Eutrophication
30. What is meant by super pest?
Super pest are immune to all types of pesticides
31. What is meant by Bio- magnification?
Bio-magnification means some pesticides that are non bio-degradable and
keep on concentrating in food chain.
32. What is meant by geothermal energy?
Geothermal energy means the energy harnessed from the high temperature
present inside the earth.
33. Distinguish between renewable and non-renewable energy resources.
S.No Renewable energy Non-renewable energy
1 It is regenerated continually Cannot be regenerated
2 In exhaustible Exhausted
34. Why alternative energy resources are required?
The alternative energy resources are required;
1) To reduce environmental pollution
2) To provide more energy
35. List out the applications of wind energy.
The applications of wind energy are:
1) It does not cause air pollution.
2) It is very cheap.
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36. What is meant by nuclear energy?
The energy produced from the nuclear reactions are called nuclear energy.
37. What is meant by biogas?
Biogas is gas obtained by fermentation of animal dung and plant wastes in
the presence of water.
38. What is meant by sustainable development?
Sustainable development is the development of healthy
environment without damaging the natural resources.
39. What is meant by sustainable forestry?
Sustainable forestry is the optimum use forest resources, which meet the
needs of the present generations.
40. State environmental impact statement.
Environmental impact is an analysis of the expected effects of a
development on the surrounding environment.
UNIT – IV
SOCIAL ISSUES AND THE ENVIRONMENT
1. What is meant by sustainable development?
Sustainable development is defined as, meeting the needs of the
present without compromising the ability of future generations to meet their own
needs.
2. State Earth Summit - 1992.
Earth summit states that “a new and equitable global partnership through the
creation of new levels of cooperation among states”
3. What is meant by 3R principle?
The approach of reduce, reuse and recycle is called as 3R principle. It insists
optimum use of natural resources, reusing instead of throwing it on the waste land
or water and recycling the material into further products.
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4. List out the objectives of rain water harvesting.
The objectives of rain water harvesting
1) To meet the increasing demands of water.
2) To raise the water table by recharging the ground water.
5. What is meant by rain water harvesting?
Rain water harvesting is a technique of capturing and storing of rain water
for further utilization.
6. What is meant by watershed?
Water shed is defined as the land area from which water drains under the
influence of gravity into a stream, lake, reservoir or other body of surface water.
7. List out the principles of watershed management.
The principles of watershed management are:
1) To minimize the risk of flood, droughts and land slide.
2) To promote social forestry and horticultural activity on all suitable areas
of land.
8. What is meant by acid rain?
Acid rain means the presence of excessive acids in rain water.
9. State any two methods to control acid rain.
The control methods of rain water are
1) Emission of SO2 and NO2 from industries should be reduced by using
pollution control equipments.
2) Liming of lakes and soils should be done to correct the adverse effect of
acid rain.
10. What is meant by acid deposition?
The presence of pollutants like NO2 and SO2 gases in atmosphere will
lowers the pH of rain water; this will increase the acidity of rain water. This type of
precipitation of water is called as acid deposition.
11. List out the effects of global warming.
The effects of global warming are:
1) Sea level increases
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2) Water resources decreases
3) Drought nature increases.
12. State the effects of ozone layer depletion.
The effects of ozone layer depletion are:
1) UV rays destroy the melamine pigments in human skin.
2) It also affects aquatic forms.
3) It degrades paints, plastics and other polymeric materials.
13. What is meant by green house effect?
The green house effect may be defined as,“ the progressive warming up
of the earth‟s surface due to blanketing effect of manmade CO2 in the atmosphere”.
14. What are green house gases?
The green house gases are the gaseous pollutants which are responsible
for green house effect. The examples of green house gases are CO2 , CH4 , nitrous
oxide (N2O) and chloro-fluoro carbons (CFCs)
15. List out few practices to reduce global warming.
The global warming can be reduced by
1) Planting more trees
2) Utilizing renewable resources such as wind, solar and hydro power
3) Shifting from coal to natural gas
16. How does climate change occur?
The climate changes occur by
1) Presence of green house gases in the atmosphere increases the
global temperature.
2) Depletion of ozone layer also increases the global temperature.
17. List out the objectives of air pollution act.
The objectives of air pollution act are
1) To prevent, control and abatement of air pollution.
2) To maintain the quality of water.
3) To establish a board for the prevention and control of air pollution.
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18. What is meant by agro forestry?
In high rainfall areas, woody trees are grown in between crops to reduce the
runoff and loss of nutrients of soil. This process of growing trees is called as agro
forestry.
19. What is meant by nuclear holocaust?
Nuclear holocaust means destruction of biodiversity by nuclear equipments
and nuclear bombs. Usually, these kinds of destruction are happened in a nuclear
war.
20. What is meant by environmental ethics?
Environmental ethics refers to the issues, principles and guidelines relating
to human interactions with their environment.
21. Distinguish between rehabilitation and resettlement of people.
Resettlement is simple relocation or displacement of human population.
This process does not focus on their future welfare.
Rehabilitation involves making the system to work again by allowing the
systems to function naturally. It includes replacing the lost economic assets,
repairing damaged infrastructures, safeguarding employment and providing safe land
for building.
22. What is wild life protection act?
Wild life protection act is aimed to protect and preserve wildlife, which was
amended in 1983, 1986, and 1991.
23. State the objectives of environment protection act.
The objectives of environmental protection act are:
1) To protect and improvement of the environment.
2) To prevent hazards to all living creatures and property.
3) To maintain harmonious relationship between humanity and their
environment.
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UNIT – V
HUMAN POPULATION AND THE ENVIRONMENT
1. What is meant by population explosion?
The enormous increase in population, due to low death rate and high
birth rate, is termed as population explosion.
2. List out the factors affecting population size.
The factors affecting population size
1) Birth rate or natality
2) Death rate or mortality
3) Immigration
4) Emigration.
3. What is meant by population stabilization?
The population stabilization ratio is derived by dividing crude birth rate
by crude death rate.
4. List out any two important views of population growth.
The important views of population growth are
1) Increased demands for food and natural resources.
2) Inadequate housing and health services.
5. What is meant by doubling time?
Doubling time is the required for a population to double its size at a
constant annual rate. It is calculated as follows
Td (Doubling time) = 70/r ; where r = annual growth rate
6. What is meant by total fertility rate?
The average number of children delivered by a woman in her life time.
The TFR value varies from 2 in developed countries to 4.7 in developing countries.
7. List out the objectives of family welfare program.
The objectives of family welfare program are
1) Achieve hundred percent registrations of births, deaths, marriage
and pregnancy.
2) Encourage late marriages and later child bearing.
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8. What is meant by NIMBY syndrome?
NIMBY means “NOT IN MY BACK YARD”, which describes the
opposition of residents to the nearby location of something they consider
undesirable, even if it is clearly a benefit for many.
9. What is meant by value education?
Value education is an instrument used to analyse our behavior and
provide proper direction to our youths. It teaches them the distinction between right and
rong.
10. State the role of primary health care against AIDS.
The role of primary health care against AIDS
1) Prevention of blood borne HIV transmission.
2) AIDS awareness programmes should be encouraged.
11. What is meant by remote sensing?
Remote sensing refers to any method which can be used to gather
information about an object without actually coming in contact with it.
12. What is meant by GIS?
Geographical information system is a technique of superimposing
various thematic maps using digital data on a large number of inters related aspects.
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EC6202 ELECTRONIC DEVICES AND CIRCUITS
UNIT-I - PN DIODEAND ITSAPPLICATIONS
1. What is depletion region in PN junction?
The region around the junction from which the mobile charge carriers
(electrons and holes) are depleted is called depletion region. Since this region has
immobile ions, which are electrically charged, the depletion region is also known
as space charge region.
2. What are the other names of depletion region?
1. Space charge region
2. Transition region
3. What is meant by barrier potential?
The oppositely charged ions present on both sides of a PN junction when an
electric potential is established across the junction even without any external
voltage source is termed as barrier potential.
4. What is meant by biasing a PN junction?
Connecting a PN junction to an external voltage source is biasing a PN
junction.
5. What are the types of biasing a PN junction?
The types of biasing a PN junction diode are,
1. Forward bias
2. Reverse bias
6. What is meant by forward bias and reverse bias in a PN junction?
When positive terminal of the external supply is connected to P region and
negative terminal to N region, the PN junction is said to be forward biased. Under
forward biased condition, the PN region offers a very low resistance and a large
amount of current flows through it.
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7. What is meant by reverse bias in a PN junction?
When the positive terminal of the external supply is connected to N type
and negative terminal to P type then the PN junction is said to be in reverse bias.
Under reverse biased condition the PN region offers a very high resistance and a
small amount of current flows through it.
8. What is meant by reverse saturation current?
The current due to the minority carriers in reverse bias is said to be reverse
saturation current. This current is independent of the value of the reverse bias
voltage.
9. Why do contact differences of potential exist in PN junction?
When a PN junction is formed by placing a p-type and n-type material in
intimate contact, the Fermi level throughout the newly formed specimen is not
constant at equilibrium. There will be transfer of electron and energy until Fermi
levels in the two sides did line up. But the valence and conduction band in p-side
cannot be at the same level as in n-side. This shift in energy level results in contact
difference of potential.
10. What is the static resistance of a diode?
Static resistance R of a diode can be defined as the ratio of voltage V across
the diode to the current flowing through the diode.
1. R = V/ I
where,
R - Static resistance of a diode
V -Voltage across the diode
I - current across the diode
11. Define – Dynamic Resistance
Dynamic resistance of a diode can be defined as the ratio of change in
voltage across the diode to the change in current through the diode.
1. r = V / I
where,
r - Dynamic resistance of a diode
V –change in voltage across the diode
I - change incurrent through the diode
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12. What is meant by an amplifier?
An amplifier is a device which produces a large electrical output of similar
characteristics to that of the input parameters.
13. Why do we choose q point at the center of the load line?
The operating point of a transistor is kept fixed usually at the center of the
active region in order that the input signal is well amplified. If the point is fixed in
the saturation region or the cut off region, the positive and negative half cycle gets
clipped off respectively.
14. When does a transistor act as a switch?
The transistor acts as a switch when it is operated at either cut off region or
saturation region.
15. What is meant by biasing?
To use the transistor in any application, it is necessary to provide sufficient
voltage and current to operate the transistor. This is called biasing.
16. What is meant by operating point?
For the proper operation of the transistor a fixed level of current and
voltages are required. These values of currents and voltages defined at a point at
which the transistor operate is called operating point.
17. Define – Luminescence
Luminescence is defined as the emission of light by a solid when it is
stimulated by the source of incident energy.
18. What are the various types of luminescence?
The various types of luminescence are,
a. Photoluminescence
b. Electroluminescence
19. Define – Photoluminescence
Photoluminescence is defined as the incident energy in the form of photons.
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20. Define – Electroluminescence
Electroluminescence is defined as the radiation which is produced by the
application of an electric field.
21. Which colour of light is emitted by GaAs, Gp and GaAsp?
GaAs - Infra red radiation (invisible)
GaP- Red or Green
GaAsP- Red or Yellow
22. Define – Injection Laser Diode
Injection laser diode is defined as the coherent emission of light i.e.
essentially monochromatic.
23. What are the limitations of LCD?
The limitations of LCD are as follows:
1. It requires an external or internal light source
2. Temperature range is limited to about60˚C
3. Lime time is limited due to chemical degeneration
24. What are the two types of LCDs?
The two types of LCD are,
1. Dynamic scattering type LCD
2. Field effect LCD
25. What are the types of various crystal materials used in LCD?
The various types of crystal materials used in LCD are as follows:
1. Nematic
2. Cholesteric
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UNIT II
1. Define – Transistor
Transistor consists of two junctions formed by sandwiching either P-
type or N- type semiconductor between a pair of opposite types.
2. Write the current amplification factor for a CB transistor.
The current amplification factor for a CB transistor is given as,
a = Change in Collector Current at constant VCB / Change in emitter current
3. Write the formula for input resistance in a CB transistor
Input resistance = Change in base - emitter voltage / Change in emitter
current at constant VCB
4. Write the current amplification factor for a CE transistor.
The current amplification factor for a CE transistor is given as,
b = Change in Collector Current / Change in base current at constant VCE
5. What is meant by transistor action?
A transistor consists of 2 coupled PN junctions. The base is a common
region to both junctions and makes a coupling between them. Since the base
regions are smaller, a significant interaction between junctions will be available.
This is called transistor actions.
6. Define – Delay Time
It is defined as the time required for the current to rise from 0 to
10% of its maximum value.
7. Define – Rise Time
It is the time required for the current to rise from 0 to 90% of the
maximum value.
8. Define – Turn-on Time
It is the time required for the current to rise from 0 to 90% of the maximum
value ton = td + tr
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9. Define – Fall Time
It is the time required for the collector current to fall from 90 to 10% of Ics.
10. Define – Storage Time
It is the time required to fall from 100 to 90% of Ics.
11. Define – Turn-off Time
It is the time required to fall from 100 to 90% of Ics. Toff=ts+tr
12. Define – Hybrid parameters.
Any linear circuit having input and output terminals can be analyzed by
four parameters(one measured on ohm, one in mho and two dimensionless) called
hybrid or h- parameters.
13. What is the use of h-Parameters?
It perfectly isolates the input and output circuits. Its source and load
currents are taken into account.
14. Define – Power Transistors
Power transistors are those which handle a large amount of current and also
dissipates large amount of power across collector base junction.
15. Which is the most commonly used transistor configuration? Why?
The CE Configuration is most commonly used.
The reasons are
1. High Current gain
2. High voltage gain
3. High power
4. Moderate input to output ratio
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UNIT - III - FET AND ITS APPLICATIONS
1. What are the advantages of FET?
The advantages of FET are as follows:
1. Input impedance is very high. This allows high degree of isolation between
the input & output circuit.
2. Current carriers are not crossing the junctions. Hence noise is highly
reduced.
3. It has a negative temperature co-efficient of resistance. This avoids the
thermal runaway.
2. What is the advantage of MOSFET over JFET?
The input impedance of MOSFET is higher than that of JFET
3. What are the two modes of MOSFET?
The two modes of MOSFET are as follows:
1. Depletion mode
2. Enhancement mode
4. Why is UJT called so?
UJT has only one PN junction. So it is called as uni junction transistor
5. What are the advantages of SCR and TRIAC?
The advantages of SCR and TRIAC are as follows:
1. SCR performs rectification, inversion and regulation of power flow
2. TRIAC is a bidirectional switch and hence it can conduct in both the
direction.
6. Define – Breakdown Voltage
Breakdown voltage is defined as the applied voltage at which the thyristors conducts
heavily without gate voltage.
7. Define – Latching Current
Latching current is defined as the minimum current required to latch the device from
OFF to ON state.
8. Define – Holding Current
Holding current is defined as the minimum current required to hold the device into
conduction.
9. Define – Turn-on Time
Turn-on time is defined as the time taken by the SCR to reach to its full conduction
from the time the trigger is applied.
10. Define – Turn-off Time
Turn-off time is defined as the finite time taken by the SCR after application of
the reverse voltage to switch the device off.
11. What are the advantage of SCR?
The various advantages of SCR are,
1. Switching speed is high
2. No moving parts
3. It gives noiseless operation at high frequency
4. It controls large current in the load by means of small gate current
5. Occupies less space
12. Write some applications of thyristor.
Applications of thyristor are,
1. Used for power control
2. Used for speed control of a DC shunt motor
13. Define – Finger Voltage
Finger voltage is defined as the minimum voltage which is required between anode
and the cathode of thyristor to trigger into conduction
14. What is the name for solid state equivalent of thyristor?
The name for solid state equivalent of thyristor is thyratron.
15. Define – Inter-base Resistance
Inter-base resistance is defined as the resistnce offered by the silicon bar.
16. Define – Pinch-off Voltage
Pinch-off voltage is defined as the drain source voltge above which the drain current
becomes constant
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17. What are the differences between JFET & BJT
S. NO. JFET BJT
1 Unipolar device Bipolar device
2 High input impedance Low input impedance due to forward
bias
3 Voltage driven device Current driven device
4 Gain is characterized by
trans-conductance gain Gain is characterized by voltage
5 Low noise level High noise level
18. What is meant by amplification factor?
It is the product of drain résistance and trans-conductance m=Rd x gm Rd=Drain
resistance, gm=Trans-conductance
19. Define – Drain Resistance
Drain resistance is defined as the ratio of change in drain source voltage to change in
drain current at constant gate source voltage.
UNIT – IV - AMPLIFIERS AND OSCILLATORS
1. Define – DC Load Line
The DC load line is defined as a line on the output characteristics of the transistor
which gives the value of Ic & VCE corresponding to zero signal condition.
2. What is the necessity of the coupling capacitor?
The necessity of the coupling capacitor is to block the DC signal to the transistor
amplifier. It allows AC & blocks the DC.
3. Why is the operating point selected at the centre of the active region?
The operating point is selected at the Centre of the active region to get to
perfect amplification. Moreover there is no distortion.
4. Define – Operational Amplifier
Operational amplifier is defined as a direct-coupled, high gain amplifier consisting of
one or more differential amplifier. By properly selecting the external components, it can be
used to perform a variety of mathematical operations.
5. What happens when the common terminal of V+ and V- sources is not grounded?
If the common point of the two supplies is not grounded, twice the supply
voltage will get applied and it may damage the op-amp.
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6. Define – Input Offset Voltage
Input offset voltage is defined as a small voltage applied to the input terminals to
make the output voltage as zero when the two input terminals are grounded is called input
offset voltage
7. Define – Input Offset Current
Input offset current is defined as the difference between the bias currents at the input
terminals of the op-amp.
8. Define – CMRR of an op-amp
The relative sensitivity of an op-amp to a difference signal as compared to a
common – mode signal is called the common –mode rejection ratio. It is expressed in
decibels.
9. In practical op-amps, what is the effect of high frequency on its performance?
The open-loop gain of op-amp decreases at higher frequencies due to the presence of
parasitic capacitance. The closed-loop gain increases at higher frequencies and leads to
instability.
10. Define – Slew rate
Slew rate is defined as the maximum rate of change of output voltage caused
by a step input voltage. An ideal slew rate is infinite which means that op-amp‟s output
voltage should change instantaneously in response to input step voltage.
11. Write any two audio frequency oscillators.
1. RC phase shift oscillator
2. Wein bridge oscillator
12. Write some of the linear applications of op – amps.
Adder, subtractor, voltage –to- current converter, current –to- voltage converters,
instrumentation amplifier, analog computation, power amplifier, etc are some of the
linear op-amp circuits.
13. Write some of the non – linear applications of op-amps.
Rectifier, peak detector, clipper, clamper, sample and hold circuit, log amplifier,
anti-log amplifier, multiplier are some of the non – linear op-amp circuits.
14. What are the areas of application of non-linear op- amp circuits?
1. Industrial instrumentation
2. Communication
3. Signal processing
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UNIT – V - PULSE CIRCUITS
1. What is meant by multivibrator?
Multivibrators are a group of regenerative circuits that are used extensively in timing
applications. It is a wave shaping circuit which gives symmetric or asymmetric square
output. It has two states stable or quasi- stable depending on the type of multivibrator.
2. What is meant by monostable multivibrator?
Monostable multivibrator is one which generates a single pulse of specified duration
in response to each external trigger signal. It has only one stable state. Application of a
trigger causes a change to the quasi-stable state. An external trigger signal generated due
to charging and discharging of the capacitor produces the transition to the original stable
state.
3. What is meant by astable multivibrator?
Astable multivibrator is a free running oscillator having two quasi-stable states.
Thus, there is an oscillation between these two states and no external signal is required to
produce the change in state.
4. What is meant by bistable multivibrator?
Bistable multivibrator is one that maintains a given output voltage level unless an
external trigger is applied. Application of an external trigger signal causes a change of state,
and this output level is maintained indefinitely until a second trigger is applied. Thus, it
requires two external triggers before it returns to its initial state.
5. What are the requirements for producing sustained oscillations in feedback circuits?
For sustained oscillations, the total phase shift around the loop must be zero at the
desired frequency of oscillation. At desired frequency, the magnitude of the loop gain A
should be equal to unity.
6. What is meant by filter?
Filter is a frequency selective circuit that passes signal of specified band of
frequencies and attenuates the signals of frequencies outside the band
7. What are the demerits of passive filters?
Passive filters work well for high frequencies. But at audio frequencies, the inductors
become problematic, as they become large, heavy and expensive. For low frequency
applications, more number of turns of wire must be used, which in turn adds to the series
resistance degrading the inductor‟s performance i.e., low Q, resulting in high power
dissipation.
8. What are the advantages of active filters?
Active filters use op- amp as the active element and resistors and capacitors as
passive elements. By enclosing a capacitor in the feedback loop, inductor less active filters
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can be obtained. Op-amp used in non – inverting configuration offers high input impedance
and low output impedance, thus improving the load drive capacity.
9. List out some commonly used active filters.
1. Low pass filter
2. High pass filter
3. Band pass filter
4. Band reject filter
10. List out some applications of 555 timer:
1. Oscillator
2. Pulse generator
3. Ramp and square wave generator
4. Mono-shot multivibrator
5. Burglar alarm
6. Traffic light control
11. List out the applications of 555 timers in monostable mode of operation:
1. Missing pulse detector
2. Linear ramp generator
3. Frequency divider
4. Pulse width modulation
12. List out the applications of 555 timers in Astable mode of operation:
1. FSK generator
2. Pulse-position modulator
13. What is meant by combinational logic?
When logic gates are connected together to produce a specified output for certain
specified combinations of input variables, with no storage involved, the resulting circuit is
called combinational logic.
14. Explain the design procedure for combinational circuits.
1. The problem definition
2. Determine the number of available input variables & required O/P variables
3. Assigning letter symbols to I/O variables
4. Obtain simplified Boolean expression for each O/P
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15. Define – Half Adder and Full Adder
The logic circuit that performs the addition of two bits is a half adder. The circuit that
performs the addition of three bits is a full adder.
16. Define – Decoder
Decoder is defined as a multiple - input multiple output logic circuits that
converts coded inputs into coded outputs where the input and output codes are different.
17. What is meant by binary decoder?
A decoder is a combinational circuit that converts binary information from n input
lines to a maximum of 2n out puts lines.
18. Define – Encoder
An encoder has 2n input lines and n output lines. In encoder, the output lines
generate the binary code corresponding to the input value.
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EE6303-LINEAR INTEGRATED CIRCUITS AND APPLICATIONS
UNIT I – IC FABRICATION
1. Write the basic chemical reaction in the epitaxial growth process of pure silicon.
(A/M-11)
The basic chemical reaction in the epitaxial growth process of pure silicon is the
hydrogen reduction of silicon tetrachloride.
At 12000C SiCl4 + 2H2 <---> Si + 4 H Cl
2. What are the advantages of integrated circuits over discrete circuits?
(A/M-11, M/J-13)
The advantages of integrated circuits over discrete circuits are
1) Miniaturization and increased equipment density
2) Cost reduction due to batch processing
3) Increased system reliability due to elimination of soldered joints
4) Improved functional performance
5) Increasing operating speeds
6) Reduction in power consumption
3. Why are inductors difficult to fabricate in IC’s? (M/J-13)
IC devices are essentially two dimensional as the depth dimension is very small
compared to the lateral dimensions. IC inductors can be made in the form of flat metallic thin
films spirals by successive deposition of conduction patterns. Very small values of
inductance of the order of nano-henry with low quality factor can only be obtained. For any
reasonable inductance value, a three dimensional coil structure is needed to obtain a large
number of turns.
4. What is the purpose of oxidation process in IC fabrication? (A/M-10)
The two main purposes of oxidation process in IC fabrication are
1. SiO2 is an extremely hard protective coating and is unaffected by almost
all reagents except hydrochloric acid. Thus it stands against any
contamination.
2. By selective etching of SiO2, diffusion of impurities through carefully
defined windows in the SiO2 can be accomplished to fabricate various
components.
5. What is meant by parasitic capacitance? (A/M-10)
In p-n junction isolation technique, there is presence of transition capacitance at the
isolating p-n junctions, resulting in an inevitable capacitor coupling between the components
and the substrate. These parasitic capacitances limit the performance of the circuit at high
frequencies.
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6. Compare monolithic IC with hybrid IC. (N/D-10)
Monolithic ICs Hybrid ICs
All circuit components and their
interconnections are manufactured on top
of a single silicon chip
All circuit components are attached to a
ceramic substrate and interconnected by
means of either metallization pattern or
wire bonds.
Ideal for applications where identical
circuits are required in very large
quantities.
More adaptable to small quantity custom
circuits
Provides lowest per-unit cost and highest
order of reliability
Provides highest per-unit cost and lowest
order of reliability
7. What is meant by lithography? (N/D-10)
Lithography is a process by which the pattern appearing on the mask is
transferred to the wafer. It involves two steps:
i. The first step requires applying few drops of photo resist to the surface of the
wafer
ii. The second step is spinning the surface to get an even coating of the photo
resist across the surface of the wafer.
8. List out the basic processes used in IC Fabrication. (N/D-11)
The basic processes used in IC Fabrication are
1) Silicon wafer (substrate) preparation
2) Epitaxial growth
3) Oxidation
4) Photolithography
5) Diffusion
6) Ion implantation
7) Isolation technique
8) Metallization
9) Assembly processing & packaging
9. What is meant by ion implantation? (N/D-11)
Ion implantation is a technique used to introduce impurities into a silicon wafer. In
this process, silicon wafers are placed in a vacuum chamber and are scanned by a beam of
high energy dopant ions.
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10. List out the various isolation techniques used in IC’s.
The various isolation techniques used in IC‟s are
1) p-n junction isolation
2) Dielectric isolation
11. List out the steps involved in the preparation of silicon wafers.
The steps involved in the preparation of silicon wafer are
1) Crystal growth &doping
2) Ingot trimming & grinding
3) Ingot slicing
4) Wafer policing & etching
5) Wafer cleaning
12. What is meant by metallization?
The process of producing a thin metal film layer that will serve to make interconnection
of the various components on the chip is called metallization.
UNIT II - CHARACTERISTICS OF OP-AMP
1. List out the characteristics of an ideal op-amp. (A/M-10)
The characteristics of an ideal op-amp are
1. Open loop voltage gain is infinite
2. Input impedance is infinite
3. Output impedance is zero
4. Bandwidth is infinite
2. Design an amplifier with a gain of –10 and input resistance of 10 kΩ. (A/M-10)
Since the gain of the amplifier is negative, an inverting amplifier has to be designed,
R1 = 10 kΩ
Rf = - ACLR1
Rf = - (-10) * 10 kΩ = 100 kΩ
3. What are the different kinds of packages of IC741? (A/M-11)
The different kinds of packages of IC741 are
1) Metal can (TO) package
2) Dual-in-line package
3) Flat package
4. What is meant by thermal drift? (N/D-11)
The bias current, offset current and offset voltage change with temperature. A
circuit carefully nulled at 25oC may not remain so when the temperature rises to 35
oC. This
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is called thermal drift. Often, offset current drift is expressed in nA / oC and offset voltage
drift in mV/ oC. These indicate the change in offset for each degree Celsius change in
temperature.
5. Define – Input Offset Voltage. (N/D-11)
A small voltage applied to the input terminals to make the output voltage as zero
when the two input terminals are grounded is called input offset voltage.
6. What is the input impedance of a non-inverting amplifier? (M/J-13)
Input impedance of a non-inverting amplifier is very high and the output voltage
follows the input voltage exactly. Hence the non-inverting circuit is also called voltage
follower.
7. Define – Slew Rate
The slew rate is defined as the maximum rate of change of output voltage caused by
a step input voltage and is usually specified in V / µs. An ideal slew rate is infinite which
means that op-amp‟s output voltage should change instantaneously in response to input step
voltage. Slew rate is an important parameter to be considered for selecting an op-amp for
high frequency applications.
8. Define – Common Mode Rejection Ratio (CMRR) of an op-amp
It is defined as the ratio of the differential mode voltage gain to common mode
voltage gain.
CMRR= ρ = Ad/Ac
9. Draw the pin configuration of IC741.
11. What are the DC characteristics of op-amp?
1) Input Bias current.
2) Input offset current.
3) Input offset voltage.
4) Thermal Drift.
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12. What are the AC characteristics of op-amp?
1) Slew rate.
2) Frequency response.
13. What are the features of IC 741?
1) No frequency compensation required.
2) Short circuit protection provided.
3) Offset voltage null capability.
4) No latch up.
5) Large common mode and differential voltage range.
UNIT III - APPLICATIONS OF OPAMP
1. What is the need for an instrumentation amplifier? (A/M-11)
In a number of industrial and consumer applications, the measurement of physical
quantities is usually done with the help of transducers. The output of transducer has to be
amplified so that it can drive the indicator or display system. This function is performed by
an instrumentation amplifier.
2. Define – Conversion Time of ADC. (A/M-11)
Conversion time of ADC is defined as the total time required for converting an
analog signal into its digital output. It depends on the conversion technique used and the
propagation delay of circuit components. The conversion time of a successive approximation
type ADC is given by
Tc = T (n+1)
where
Tc conversion time
T clock period
n no. of bits.
3. Draw the circuit diagram of an op-amp based positive clipper. (N/D-10)
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4. Which is the fastest ADC and why? (N/D-10)
The parallel or flash type ADC is the fastest ADC because it has high speed, as the
conversion takes place simultaneously rather than sequentially.
5. Draw the circuit of first order active filter. (N/D-11)
6. Draw the circuit diagram of sample and hold circuit. (N/D-11)
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7. List out the applications of analog multipliers. (M/J-13)
1) In communication circuits for angle, phase or frequency modulation
2) In instrumentation and control for the measurement of velocity, position etc.
3) For voltage controlled attenuators
4) For frequency converters, frequency doublers and frequency shifters
5) For squaring and square-root calculations
6) In oscillators and various waveform generators
8. Write the significance of lock in range of Phase Locked Loop (PLL). (M/J-13)
Once the PLL is locked, it can track the frequency changes in the incoming signals.
The range of frequencies over which the PLL can maintain lock with the incoming signal is
called lock in range.
9. An 8 bit DAC has a resolution of 20mV/bit. What is the analog output voltage for the
digital input code 00010110 (the MSB is the left most bit)? (A/M-10)
Vo= Resolution * D
Given:
Resolution = 20mV/bit
D = equivalent of 00010110 = 22
Solution:
Vo= (20 * 10 ^ (-3)) * 22 = 0.44 V
UNIT IV
1. Why Vco is called voltage to frequency converter. (N-12)
` The VCO provides the linear relationship between the applied voltage & the
output frequency. So it is known as voltage to frequency converter.
2. In an astable multivibrator using 555 timer, RA = 6.8 kΩ, RB = 3.3 kΩ, C=0.1 μF.
Calculate the free running frequency. (N-12)
Time for one cycle, T=0.693(RA+2RB) C
RA=6.8kΩ
RB=3.3kΩ
C=0.1µF
T=0.693(6.8*103+2*3.3*10
3)*0.1*10
-6
=1.157msec
f = = 864.07Hz
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3. List out the applications of 555 timer. (M-12)
The applications of 555 timer are:
(1) Astable multivibrator
(2) Monostable multivibrator
(3) Frequency divider
(4) Pulse width modulation
4. Draw the pin diagram of IC 555 timer. (M-10)
5. Draw the basic block diagram of a PLL IC? (M-10)
6. What is meant by lock range in a PLL? (M-09)
When PLL is in lock, it can trap frequency changes in the incoming signal. The range
of frequencies over which the PLL can maintain lock with the incoming signal is called as
lock range.
7. List out the applications of VCO. (M-11)
The applications of VCO are:
(1) FM Modulation
(2) Signal generation
(3) In frequency multipliers
(4) Tone generation
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8. List out the features of 555 timer circuit. (N-09)
The features of 555 timer are:
(1) It has two operating modes – monostable and astable.
(2) It has a high temperature stability.
9. List out the applications of Analog multiplier. (N-08)
It is used in the following applications:
(1) In frequency converters
(2) In communication, in amplitude modulation and in frequency modulation.
10. Define – Pull-in Time
Pull-in time is defined as the total time taken by the PLL to establish lock.
UNIT V - APPLICATION IC’s
1. List out the important parts of regulated power supply. (A/M-10)
The important parts of regulated power supply are:
(1) Transformer
(2) Rectifier
(3) Filter
(4) Regulator
2. What are the advantages of switch mode power supplies? (A/M-10)
The advantages of switched mode power supply are
(1) Low power dissipation
(2) High efficiency
(3) Small size
(4) High power handling capacity
3. Define – Line Regulation.
Line regulation is defined as the percentage change in the output voltage for a change
in the input voltage. It is expressed in milli volts or as a percentage of the output voltage.
4. List out the important advantages of opto-couplers. (A/M-11)
The important advantages of opto-coupler are:
1) Better isolation between the two stages.
2) Impedance problem between the stages is eliminated
3) Wide Frequency response
4) Easily interfaced with digital circuit
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5. What are the advantages of LM 317 regulator over fixed voltage regulator?
The advantages of LM 317 regulator over fixed voltage regulator are:
1) Improved line & load regulation by a factor of 10 or more
2) Improved reliability for the power supply
3) Improved overload protection i.e., greater load current can be drawn over the given
operating temperature range
6. Using LM380 draw the circuit for audio power amplifier. (N/D-10)
7. What are the disadvantages of linear voltage regulators? (N/D-11)
The disadvantage of linear voltage regulators are:
(1) The efficiency of linear regulators are very low of the order of 40-50%.
(2) Large heat sink for the power transistor is required that makes the regulator bulky.
(3) Bulky transformers are required.
8. What is meant by isolation amplifier? 0 (N/D-11)
An isolation amplifier is an amplifier that offers electrical isolation between its input
and output terminals.
9. What is the function of voltage regulator? (M/J-13)
The function of voltage regulator is to provide stable DC voltage for powering other
electronic circuits.
10. What is the principle of switched mode power supplies? (M/J-13)
The SMPS is a series regulator where a pulse generator generates rectangular pulses
which are applied to the control terminal of an electronic switch. This switch is turned on and
off with the help of the rectangular pulses. Here the average output voltage is dependent on
the duty cycle D.