ee6201 circuit theory

8/16/2019 EE6201 Circuit Theory

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VALLIAMMAI ENGINEERING COLLEGE EE6201- CIRCUIT THEORY

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VALLIAMMAI ENGINEERING COLLEGE

SRM NAGAR, KATTANKULATHUR – 603203

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

Question Bank

Programme : BE

Subject : EE6201-CIRCUIT THEORY

Semester / Branch : II/EEE,ECE &EIE

UNIT-I

PART-A1. Define Ohm’s Law (B.L.T- 1)2. List and define Kirchoff’s Laws for electric circuits. (B.L.T- 1)

3. An 1Φ 50 Hz ac supply system has the RMS values of 100V, 10 A.

Examine the instantaneous value of voltage and current. (B.L.T- 3)

4. Summarize the classifications of Circuit elements (B.L.T- 2)5. Analyze how are the following affected by change of frequency

a) Resistance b) Inductive reactance. (B.L.T- 4)

6. Define ideal voltage source (B.L.T- 1)

7. Define active elements and passive elements. (B.L.T- 1)

8. Distuinguish between series and parallel circuit (B.L.T- 2)9. Select the value of R1 and R2 when they are parallel with the following

conditions. The current in R1 is twice the current flowing through R2 andthe equivalent resistance of the parallel combination is 10/3Ω. (B.L.T- 5)

10.Point out the magnitude of currents in the Ammeter of resistance 10Ω(B.L.T- 4)

11.A resistance of 120Ω and a capacitive reactance of 250Ω are connected in

series across an AC voltage supply. If a current of 0.9 A is flowing in the

circuit calculate the power factor. (B.L.T- 3)12.Measure the equivalent conductance Geq of the circuit shown below

(B.L.T- 5)


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13.Two inductances L1=3mH and L2=6mH are connected in parallel.

Analyse and infer Leq (B.L.T- 4)

14.Compose the equivalent resistance for the following combination of resistor and source current (B.L.T- 6)

15.Generalize the expressions for mesh current equations in matrix form(B.L.T- 6)

16.Define power factor. (B.L.T- 1)17.Describe the term phasor (B.L.T- 1)18.Differentiate active and reactive power in electrical circuits (B.L.T- 2)19.How do you differentiate Power and Energy in Electrical Circuits?

(B.L.T- 2)

20.Calculate the power absorbed by each of the elements in a given circuit.

(B.L.T- 3)

PART – B

1. Interpret the current delivered by the source shown in the circuit below.


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(B.L.T- 2)

2. For the network shown below, label the current ratio (I1/I3) by applying

mesh analysis. (B.L.T- 1)

3. Tabulate a) the equivalent resistances across the terminals of the supply,

b) total current supplied by the source and c) power delivered to 16 ohmresistor in the circuit shown in figure (B.L.T- 1)

4. Analyze the mesh currents I1 and I2 for the given circuit shown below(B.L.T- 4)


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5. Determine the value of V2 such that the current through the impedance(2+j3) ohm is zero (B.L.T- 3)

6. Use Nodal Voltage method and estimate the power dissipated in the 10Ω resistance on the circuit shown in the fig (B.L.T- 2)

7. (i) Derive and list the expressions for resistors in series and parallel(8 marks) (B.L.T- 1)

(ii) Quote the Kirchoff’s current law and prove it by using the definition of

Current (8 marks) (B.L.T- 1)

8. Calculate loop currents by mesh analysis (B.L.T- 3)


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9.In a circuit consisting of two elements in series, the equations for voltage andcurrent are i=28sin(314+60º) and e=180 sin 314t formulate and obtain a) the

RMS value of the voltage and current b) the frequency c) the power factor d)

the power e) the values of circuit constants. (B.L.T- 6)10.Evaluate the current in each branch and total power consumed by the circuit.

Assume E = 50 sin (ωt+45). (B.L.T- 5)

UNIT-II

PART-A

1. Explain how voltage source with a source resistance can be

converted into an equivalent current source. (B.L.T- 4)

2. Analyse the current flowing through the resistors R1 and R3 if current through R2 is 1A (B.L.T- 4)

3. Calculate The Equivalent Current Source for a Voltage Source Of

10v In Series With A 60ohm Resistance. (B.L.T- 3)4. Illustrate the equivalent voltage source for a current source of 15A


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when connected in parallel with 5 ohm resistance (B.L.T- 3)

5. Given that the resistors Ra, Rb and Rc are connected electrically in

star. Formulate the equations for resistors in equivalent delta. (B.L.T- 6)

6. Three resistors Rab, Rbc and Rca are connected in delta. Re-write the

expression for resistors in equivalent star (B.L.T- 6)7. How will you express the Norton’s equivalent circuit from Thevenin’s

equivalent circuit? (B.L.T- 2)8. State Superposition theorem (B.L.T- 1)

9. Describe the theorem used in converting an electrical circuit into oneequivalent resistance in series with voltage source (B.L.T- 1)

10.Identify the theorem used in converting an electrical circuit into one

equivalent resistance in parallel with current source (B.L.T- 1)

11. State Maximum power transfer theorem (B.L.T- 1)12.Define reciprocity theorem (B.L.T- 1)

13.A voltage source has internal impedance (4+j5) ohm. Measure the load

impedance for Maximum power transfer (B.L.T- 5)

14. Is reciprocity theorem applied to the circuit having resistors, capacitors

and diodes? Give your reason (B.L.T- 2)15.Three resistors A,B and C are connected in parallel and takes 2.5

A,IB=2IC Interpret(a) IB and IC (b)the line voltage and (c)RB and RC(B.L.T- 2)

16. Describe the concept of current division in a circuit. (B.L.T- 1)17.Using superposition theorem, calculate current in the circuit. (B.L.T- 3)

18.Discuss some applications of maximum power transfer theorem (B.L.T- 2)19.Point out the limitations of superposition theorem? (B.L.T- 4)

20.Convince the purpose of star delta transformation. (B.L.T- 5)

PART-B

1. Deduce the expressions for star connected arms in terms of delta

connected arms and delta connected arms in terms of star connected arms(B.L.T- 5)


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2. Determine the Thevenin’s equivalent for the figure and develop the

Norton’s equivalent from the same (B.L.T- 6)

3. Using star-delta transformation, in the following wheat stone bridge

circuit of figure. Calculate i)the equivalent resistance between P&Qii)the total current (iii)the current through the 18Ω resistor (B.L.T- 3)

4. Using source transformation, replace the current source in the circuit

shown below by a voltage source and solve for the current delivered by

the 50V source (B.L.T- 3)

5. Analyze the given circuit and obtain Norton’s equivalent circuit (B.L.T- 4)


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6. (i) For the circuit shown below, express the voltage across (2+j5) Ω

impedance by using Superposition theorem. (8 marks) (B.L.T- 2)

(ii) Discuss in detail and prove that, in a pure resistive circuit,RL=RThusing Maximum power transfer theorem. (8 marks) (B.L.T- 2)

7. Give Thevenin’s equivalent across the terminals AB for the circuit shown

in figure below. (B.L.T- 2)

8. Using superposition theorem identify the current through (2+j3)

ohm impedance branch of the circuit shown. (B.L.T- 1)


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9. (i) Examine the value of RL so that maximum power is delivered to

the load resistance shown in figure. (8 marks) (B.L.T- 1)

(ii) Define and explain reciprocity theorem. (8 marks) (B.L.T- 1)

10.Examine and identify the maximum power delivered to the load in the

circuit (B.L.T- 1)

UNIT-III

PART-A

1. Define mutual inductance. (B.L.T-1)2. Express the dot rule. (B.L.T-2)

3. Calculate the total inductance of the circuit, if the coefficient of

coupling(k) between the two coils 0.6 as shown in fig. (B.L.T-3)

4. Define quality factor of a series resonant circuit. (B.L.T-1)


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5. Illustrate the quality factor of a coil for the series resonant circuit

consisting of R= 10 ohm, L= 0.1 henry and C= 10 micro farad.(B.L.T-3)6. Define quality factor Q of a coil (B.L.T-1)

7. Design the frequency response of double tuned circuit. (B.L.T-6)

8. Describe bandwidth of the circuit? (B.L.T-2)9. Define coefficient of coupling. (B.L.T-1)10.Design the frequency response of RLC series circuit. (B.L.T-6)11.Give the expression which relates the self and mutual inductance.(B.L.T-2)

12. Define bandwidth of a resonant circuit. (B.L.T-1)13.Give the applications of tuned circuits. (B.L.T-2)

14.A series resonance circuit has a bandwidth of 20kHz and a quality factor

of 40. The resistor value is 10k ohm. Evaluate the value of L of this

circuit. (B.L.T-4)15.When do you say that a given AC circuit is at resonance? (B.L.T-1)

16. Analyse resonant frequency in terms of half power frequencies.(B.L.T-4)

17. Judge, When the power is maximum in the series resonance circuits?

Why?

(B.L.T-5)18. Examine the maximum possible mutual inductance of two inductively

coupled circuits with self inductance L1=25mH and L2=100mH. (B.L.T-3)

19. Compare the properties of series and parallel resonant circuits. (B.L.T-4)20.Deduce the resonant frequency and quality factor for the circuit shown

(B.L.T-5)

PART-B

1. With neat illustration and necessary derivations, describe the linear

transformer (B.L.T-1)

2. Define and derive the mutual inductance and the coupling coefficient of

the transformer with necessary illustration. (B.L.T-1)

3. Impedance Z1and Z2 are parallel and this combination is in series with animpedance Z3 connected to a 100V, 50 Hz ac supply. Z1=(5-jXc) ohm,


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Z2=(5+j0) ohm, Z3=(6.25+j1.25) ohm. Analyse the value of capacitance

such that the total current of the circuit will be in phase with the total

voltage. Find the circuit current and power. (B.L.T-4)

4. The switch in the circuit shown in fig is moved from position 1 to 2 at

t=0. Evaluate the expression for voltage across resistance and capacitor,

energy in the capacitor for t>0 (B.L.T-5)

5. For the circuit shown in fig., calculate the impedance at resonantfrequency, 10Hz above resonant frequency, and 10Hz below resonant

frequency (B.L.T-3)

6. Describe how to derive Q factor of parallel resonance (B.L.T-1)7. (i) For the circuit shown below, express the frequency at which the circuit

resonates. Also calculate the voltage across the inductor at resonance and

the Q factor of the circuit. (8 marks) (B.L.T-2)

(ii) The number of turns in two coupled coils are 500 turns, 1500 turns

respectively. When 5A current flows in coil 1, the total flux in this coil is0.6* 10

-3Wb and the flux linking the second coil is 0.3*10

-3Wb.

Calculate L1, L2, M and K. (8 marks) (B.L.T-3)8. (i) A coil having an inductance of 100mH is magnetically coupled to

another coil having an inductance if 900mH. The coefficient of coupling


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between the coils is 0.45. Predict the equivalent inductance if the two

coils are connected in (4+4 marks) (B.L.T-2)a) Series aiding and Series opposing

b) Parallel aiding and Parallel opposing

(ii) What are coupled circuits? Sketch the frequency response of a single

tuned circuit and give the explanation of tuned circuits.

(B.L.T-6) (8 marks)9. For a series RLC circuit: Derive the condition for resonance, explain the

frequency response and also obtain quality factor and bandwidth.(B.L.T-4)

10. Discuss the following (B.L.T-2)

(i) Co-efficient of coupling (8 marks)(ii) Tuned circuit (8 marks)

UNIT-IV

PART-A

1. Define Step function? (B.L.T-1)

2. Describe an initial condition? (B.L.T-1)

3. Define transient? (B.L.T-1)

4. Describe steady state value? (B.L.T-1)

5. List the periodic inputs? (B.L.T-1)

6. Quote the term time constant of a transient response. (B.L.T-1)7. Give time constant of a RL & RC circuit. (B.L.T-2)

8. Distinguish between free and forced response. (B.L.T-2)

9. Describe about Critical damping? (B.L.T-1)10.Analyze the current given by I (t) = 5 – 4 e-20t (B.L.T-4)

11. Design the equivalent circuit at t=0+ for a capacitor with initial charge of of q=0. (B.L.T-6)

12. Develop an equivalent circuit for inductor and capacitor at t=0+ when

there is no initial energy. (B.L.T-6)

13. A coil having a resistance of 10 KΩ and inductance of 50mH is

connected to a 10 volts, 10KHz power supply. Calculate the impedance(B.L.T-3)

14. In a series RLC circuit, L=2H and C= 5uF. Calculate the value of R to

give critical damping. (B.L.T-3)

15. Distinguish between transient response and steady state response of a

circuit. (B.L.T-2)


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16. A series RL with R=100Ω and L=20H has a dc voltage of 200V applied

through a switch at t=0. Assuming the initial current through the inductor

at t=0 is zero, evaluate the current at t=0.5sec (B.L.T-5)

17. Define a two port network (B.L.T-1)

18. Discuss z- and y- parameter of a typical four terminal network .( B.L.T-2)19.Summarize h parameter and give its applications. (B.L.T-2)

20. In a two port network, Z11=100Ω, Z21=120Ω, Z12=120Ω, Z22=50Ω.

Calculate Y parameters. (B.L.T-3)

PART-B

1. Express the step responses of RL and RC circuits. Compare their

performances. (B.L.T-2)

2. Give the expression for current response of RLC series circuit withsinusoidal excitation. Assume that the circuit is working in critical

damping condition. (B.L.T-2)3. (i) A series RC circuit with R=5 KΩ and C=20uF as a constant voltage

source of 100V applied at t=0; there is no initial charge on the capacitor.

Examine the current i and charge q for t > 0 (8 marks) (B.L.T-1)(ii) In the circuit given below, the switch has been in position 1 for

sufficient time to establish steady state conditions. The switch is then

moved to position 2.show the current transient (8 marks) (B.L.T-3)

4. (i) Analyze the expression for current transient when series RL circuit is

excited by a sinusoidal source v=Vm(sin ωt) at t=0 (8 marks) (B.L.T-4)

(ii)A series RLC circuit with R=50Ω, L=0.1H and C=50uF as a voltage

of 100V applied to it at t=0 through a switch. Evaluate the expression for

a current transient. Assume initially relaxed circuit conditions(8 marks) (B.L.T-5)

5. (i) Using laplace transform analyze expression for i1 and i2 in the circuitshown below, when dc voltage source is applied suddenly. Assume that

initial energy stored in the circuit is zero. (8 marks)( B.L.T-4)


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VALLIAM

SRM

DEPARTMENT OF

(ii) In the circuit s

current. The initial

6. In the circuit sho

switch is closed at

charge on the capa

VALLIAMMAI ENGINEERING COLLEGE EE6

MAI ENGINEERING C

NAGAR, KATTANKULATHUR – 603203

ELECTRICAL AND ELECTRONICS E

hown below examine the expression

current is shown in the figure (8

n describe about the expression f

t=0 and the value of current at t=1m

itor is zero

201- CIRCUIT THEORY

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LLEGE

GINEERING

for the transient

marks) (B.L.T-1)

r current if the

. Assume initial

(B.L.T-1)


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VALLIAM

SRM

DEPARTMENT OF

7. In the series circui

t=0. At t=1ms, thefor the current in b

8. A series RC circui

of 200Sin(500t) vcharge on the capa

9. (a) Examine the tr

using laplace transi. Deriv

ii. Discuunder

(b) In a T netwo

calculate the Z par

10. (i) Evaluate the Z


MAI ENGINEERING C



shown in figure, the switch is closed

switch is moved to position 2. Interpth intervals and draw the transient cur

with R=100Ω and C=25uF is suppli

lt. Express the current in the circuititor is zero.

ansient response of series RLC circui

orm.

the necessary differential equation an

s the cases of over damping, Criticdamping

rk shown in fig Z1=2∟0°, Z2=5∟-

meters (8

arameters for the circuit shown in fig(8

201- CIRCUIT THEORY

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LLEGE

GINEERING

on position 1 at

ret the equations rent curve.

(B.L.T-2)

d with a source

. Assume initial (B.L.T-2)

t with DC input

(B.L.T-1)

d solve.

al damping and

0°, Z3=3∟90°,

marks) (B.L.T-3)

marks) (B.L.T-5)


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VALLIAM

SRM

DEPARTMENT OF

(ii) Express Y para

1. Describe the effect

2. List the advantages3. List out the metho

4. Give the distortion

5. List out the metho6. Identify the voltag

voltage across R a

7. Distinguish betwee

8. Give the equations

delta connected net

9. A 3Φ 400V sup

impedance 8+j6 oh10.A 3Φ motor can b

5.6kW when the li

motor


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meters of network shown in fig from(8

UNIT-V

PART-A

of power factor in energy consumptio

of 3Φ system over 1Φ

s of power measurement in 3Φ circuit

power factor equation of three phase c

s of power measurement in 3Φ circuit

across Y and B in a 3 Φ balanced d

d Y is 400∠00

V. Assume RYB phase

n unbalanced source and unbalanced l

for the phasor difference between the

works.

ly is given to a balanced star co

ms in each branch. Estimate the line c e regarded as a balanced Y load. A

ne current is 18.2A. Estimate the po

201- CIRCUIT THEORY

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LLEGE

GINEERING

parameters.marks) (B.L.T-2)

billing(B.L.T-1)

(B.L.T-1)

(B.L.T-1)

ircuits. (B.L.T-1)

.(B.L.T-1)

elta system with

sequence(B.L.T-1)

ad. (B.L.T-2) potentials of the

(B.L.T-2)

nected load of

rrent (B.L.T-2) Φ motor draws

er factor of the

(B.L.T-2)


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11. In the measurement of three phase power using two wattmeter method,

predict when both the wattmeter read same values, what is the value of

power factor of the load? (B.L.T-2)

12.Describe measurement of reactive power using wattmeter. (B.L.T-2)

13.Three coils, each having resistance of 20Ω and an inductive reactance of

15Ω are connected in star to a 400V, 3Φ and 50Hz supply. Calculate a)

line current, b) power factor and c) power supplied. (B.L.T-3)14.Calculate the power factor if V(t)=Vmsin(ωt-45

0) and I(t)=Imsin(ωt-135

0)

(B.L.T--3)15. Calculate the power factor if V(t)=Vmsinωt and I(t)=Imsin(ωt -45

0)

(B.L.T--3)

16.Explain balance supply system. (B.L.T-4)

17. In two wattmeter power measurement method, if one wattmeter reads

zero, analyze the power factor of the circuit. (B.L.T-4)18.Compare star and delta connected system. (B.L.T-4)

19. Summarize the main objectives of interconnection of the phases?(B.L.T-5)

20.Develop the circuit diagram for balanced delta connected load. (B.L.T-6)

PART-B

1. Discuss in detail about the three phase 3-wire circuits with star connected

balanced loads. (B.L.T-2)2. Explain in detail the phase diagram of voltages and currents of a three

phase unbalanced loads. (B.L.T-5)

3. A symmetrical three phase three wire 440v supply to a star connected

load. The impedance in each branch are =2+j3Ω, =1-j2Ω and

=3+j4Ω. Calculate its equivalent delta connected load. (B.L.T-3)

4. A three phase balanced delta connected load of 3+j4Ω is connectedacross a 400v, 3 phase balanced supply. Examine the phase currents and

line currents (Phase sequence in RYB). (B.L.T-1)

5. A balanced delta connected load takes a line current of 15 A when

connected to a balanced 3 phase 400 v system. A wattmeter with its

current coil in one line and Potential coil between the two remaining linesread 2000W. Describes the load impedances. (B.L.T-1)

6. Develop the expression for balanced delta connected load and draw the

phasor diagram. (B.L.T-6)


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7. Explain three phase power measurement by 2 wattmeter method for star

and delta connected load and determine the power equation and draw the

phasor diagram. (B.L.T-4)

8. Give the short notes on symmetrical components and un-symmetrical

components. (B.L.T-1)9. The two wattmeter methods produces wattmeter readings P1=1560W and

P2=2100W When connected to delta connected load. If the line voltage is

220V, Calculate (1) the per phase average power (2) the per phase

reactive power. (3) the power factor (4) the phasor impedance. (B.L.T-3)10. Describe about the various methods to measure the real power and power

factor in the three phase circuits (B.L.T-2)BLOOM’S TAXONOMY

PART A BTL 1 BTL 2 BTL 3 BTL 4 BTL 5 BTL 6

UNIT 1 6 4 3 3 2 2

UNIT 2 6 4 3 3 2 2

UNIT 3 6 4 3 3 2 2

UNIT 4 6 4 3 3 2 2

UNIT 5 6 4 3 3 2 2

Total 30 20 15 15 10 10

PART B BTL 1 BTL 2 BTL 3 BTL 4 BTL 5 BTL 6

UNIT 1 3 2 1 2 1 1

UNIT 2 3 2 1 2 1 1

UNIT 3 3 2 1.5 2 1 0.5

UNIT 4 3 2 1 2 1 1

UNIT 5 3 2 2 1 1 1

Total 15 10 5.5 9.5 5 5

ee6201 circuit theory

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