physics laboratory manual i b.sc., ii semester
TRANSCRIPT
Department of Physics, GFGC, Thirthahalli.
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PHYSICS LABORATORY MANUAL
I B.Sc., II SEMESTER
DEPARTMENT OF PHYSICS
GOVERNMENT FIRST GRADE COLLEGE
THIRTHAHALLI
Department of Physics, GFGC, Thirthahalli.
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LIST OF EXPERIMENTS
1. ‘q’ by uniform bending
2. ‘q’ by single cantilever
3. Sonometer
4. Torsional pendulum
5. Viscosity of water
6. Volume resonator
7. Surface tension by drop weight method
8. Surface tension of water by capillary rise method
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: ‘q’ BY UNIFORM BENDING
AIM: To determine young’s modulus (q) of the material of the given bar by
method of uniform bending.
APPARATUS: Bar, two knife edges, two scale pans, slotted weight of 50
grams, travelling microscope, slide calipers, screw gauge, a bright pin.
PROCEDURE: The experimental arrangements are made as shown in figure.
Bright pin is fixed vertically at the center of the bar. Care is taken to see that
knife edges and scale pans are symmetrically placed from the two edges of the
bar.
Some dead load is added to the scale pan. A travelling microscope is set in front
of the arrangement and eyepiece is focused and its height is adjusted such that
the tip of the pin coincides with a horizontal cross wire.
The reading on the vertical scale is noted. Equal weights in steps of 50 g are
added equally to the scale pan in increasing steps. In each case microscope is
adjusted by increasing in height in one direction only and the corresponding
reading for the tip of the pin is noted. The experiment is repeated for different
loads. Observations are tabulated. The elevation (y) for different loads (m) are
noted.
A graph of the load against elevation is plotted. The slope of the straight line is
found. Using the meter scale, the distance between the knife edges and scale is
measured. Using a screw gauge, the thickness (d) of the bar is determined.
Using vernier calipers, the average breadth of the bar is measured.
The young’s modulus of the material of the bar is calculated using the formula,
RESULT: Young’s modulus of the material of the given bar, q = ______ Nm-2
.
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OBSERVATIONS:
FORMULA USED:
Where, g = acceleration due to gravity in m/s2.
x = distance between knife edge and scale pan in m.
= distance between two knife edges in m.
b = mean breadth of bar in m.
d = mean thickness of bar in m.
EXPERIMENTAL SET UP:
NATURE OF GRAPH:
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TABLE-1: To determine elevation for different loads:
L.C. of travelling microscope =
= -------cm
Distance between two knife edges, l = _______________m.
Distance between knife edge & scale pan, x = _____________m.
TABULAR COLUMN:
Load in
Kg
Reading in cm Mean reading
in cm
Elevation y in
cm Load increasing Load decreasing
TABLE-2: To determine the thickness of bar:
Pitch of screw gauge, P =
= ---------
L.C. of screw gauge, LC =
= ----------mm.
Zero error with sign, ZE = ___
TABULAR COLUMN:
Trial
no.
PSR in mm HSR in
division
TR=PSR+(HSR-Z)LC in mm Mean [d] in
mm
Mean thickness, d=__________m.
CALCULATIONS:
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Expt. Name: ‘q’ BY SINGLE CANTILIVER
AIM: To determine young’s modulus (q) of the material of the cantilever by
graphical method.
APPARATUS: Cantilever, rigid support, slotted weight of 50 grams, travelling
microscope, slide calipers, screw gauge, a bright pin.
PROCEDURE: One end of the given material in the form of a thin bar is fixed
firmly by means of a given clamp on a support, so that cantilever is projected.
At the other end of the cantilever bar, a scale pan is attached. A bright pin is
fixed vertically at the position of the scale pan by means of wax. A travelling
microscope is set in front of the cantilever and its eyepiece is focused to the tip
of the pin, so that horizontal cross wire coincide with the tip of the pin.
A convenient dead load is placed on the scale pan. The sight of the eyepiece is
carefully decreased only in the one direction and tip of the pin is made to
coincide with the horizontal cross wire, the reading is noted.
Next, convenient slotted weights are added to the scale pan in equal steps and in
each step the reading of the tip of the pin is noted by decreasing the height of
the microscope.
The experiment is repeated by decreasing the load in steps. The average reading
for a particular load is calculated. From these observations, the depression of the
cantilever is calculated for different loads.
Using a meter scale, the length of the cantilever (l), the distance between the
fixed end to the point of suspension of scale pan is measured. Using a screw
gauge, the average thickness (d) of the bar is measured. Using a vernier calipers,
the average breadth (b) is measured. A graph of load vs depression is plotted.
The slope of the straight line is calculated. Young’s modulus of the material of
the cantilever is calculated using the relation,
RESULT: Young’s modulus of the material of the cantilever, q = _____ Nm-2
.
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OBSERVATIONS:
FORMULA USED:
Young’s modulus,
Where, g = acceleration due to gravity in ms-2.
= length of cantilever in m.
b = mean breadth of cantilever in m.
d = mean thickness of cantilever in m.
EXPERIMENTAL SET UP:
NATURE OF GRAPH:
TABLE-1: To determine depression for different loads (M):
L.C. of travelling microscope, L.C. =
= -------- cm.
Length of the cantilever, l = __________m.
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TABULAR COLUMN:
Load in
Kg
Reading in cm Mean reading
in cm
Depression y
in cm Load increasing Load decreasing
TABLE-2: To determine the thickness of bar:
Pitch of screw gauge, P =
= --------- mm.
L.C. of screw gauge, LC =
= ---------- mm.
Zero error with sign, Z = ____
TABULAR COLUMN:
Trial
no.
PSR in mm HSR in
division
TR=PSR+(HSR-Z)LC in mm Mean (d) in
mm
Mean thickness, d= ________m.
Breadth of the cantilever, b = ________m.
CALCULATIONS:
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: SONOMETER
AIM: To determine the frequency of AC by using sonometer.
APPARATUS: Sonometer, electromagnets, step down transformer, weight
hanger, slotted weights etc.
PROCEDURE: The sonometer is set on the experimental table. Weight of 1Kg
is placed on the hanger, the tension T on the hanger is calculated using the
formula, T = (W+x)g in Newton. Where, x is the weight of the hanger and W is
the weight added to the hanger.
The electromagnet is held at the center position of sonometer wire between the
two bridges, such that flat surface of the electromagnet is about one centimeter
above the wire. The terminals of the electromagnet are connected to the output
terminals of the transformer and transformer is connected to the mains.The
circuit is closed. The wire of the sonometer vibrates. The movable bridges are
adjusted on either side, such that the wire is made to vibrate in a single loop
having maximum amplitude.
At this stage, the frequency of wire is equal to frequency of electromagnet so
that resonance occurs. The resonating length (L) of the wire is measured. The
experiment is repeated by increasing tension by 0.5Kg weight for four trials. A
graph of T against l2 is plotted. The slope of the straight line is calculated.
About 1 meter length of a sonometer wire is weighed using a physical balance.
If M is the mass of the wire of length L, the mass per unit length of the wire is
calculated using the formula,
Kgm
-1 and Frequency of AC is calculated
using the formula,
√
.
Observations are tabulated as shown.
RESULT: Frequency of AC, n = ____ Hz.
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OBSERVATIONS:
FORMULA USED:
Frequency of AC,
√
Where, N = frequency of wire in resonance with electromagnet.
T = Tension in Newton.
l = resonating length in m.
m = linear density in Kgm-1
.
EXPERIMENTAL SET UP:
NATURE OF GRAPH:
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Observations:
Mass of the L meter length (sonometer wire), M = ________Kg.
Length of the sonometer wire, L = _____m.
Mass per unit length, m =
= _________Kgm
-1.
Weight of hanger, x = _______Kg.
TABULAR COLUMN:
Trial
no.
Weight in
hanger in Kg (x)
Tension
T=(W+x)g in N
Resonating
length ‘l’ in m
in
CALCULATIONS:
Frequency of AC,
√
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: TORSIONAL PENDULUM
AIM: (a) to determine moment of inertia of an irregular body using a regular
body. (b) To determine rigidity modulus of the wire used.
APPARATUS: Irregular body, circular disc, steel wire with chuck nut, stop
clock, screw gauge etc.
PROCEDURE: The Torsional pendulum with circular disc, the axis being
passing at its center is set on experimental table as shown in figure. The circular
disc is set into free Torsional oscillations using the index. 20 oscillations are
counted and time for 20 oscillations is noted using a stop clock. Experiment is
repeated for 3 trials and average time for 20 oscillations is calculated.
Next the circular disc is replaced by the given irregular body and again the
period of oscillations of Torsional pendulum is determined. Using a thread,
circumference of circular disc and hence its radius R is determined. The mass of
circular disc M is found using a balance.
Then, moment of inertia of the disc is calculated using the formula,
in
Kgm2
about an axes passing through its center.
The moment of inertia of an irregular body is then calculated using the formula,
in Kgm2.
Using a screw gauge, the average radius of the suspension wire of the Torsional
pendulum is determined. Using a meter scale, the length ‘l’ of the wire is
determined.
The rigidity modulus of the material of the wire is given by,
Nm-2
RESULT: Moment of inertia of regular body, I = ________ kgm2.
Moment of inertia of an irregular body, = ________ kgm2.
Rigidity modulus of material of wire, = ________Nm-2
.
Department of Physics, GFGC, Thirthahalli.
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OBSERVATIONS:
FORMULA:
(a) Moment of inertia of circular body,
in Kgm
2
Where, M = Mass of disc in Kg.
R = Radius of circular disc in m.
(b) Moment of inertia of irregular body,
in Kgm
2
Where, Tx = Period for irregular body in sec.
T = Period for circular body in sec.
(c) Rigidity modulus of wire,
Nm-2
.
Where, l = length of the wire in m.
r = radius of the wire in m.
EXPERIMENTAL SET UP:
Mass of the circular disc, M = _______ Kg.
Radius of the circular disc, R = ________ m.
Length of the wire, l = __________m.
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Table-1: To determine period of regular body about its centre:
TABULAR COLUMN:
No. of
oscillations
Time in
sec.
No. of
oscillations
Time in sec.
Time for 20
oscillations
Mean
0
5
10
15
20
25
30
35
Period, T =
= ------------- sec.
TABLE-2; To determine period of irregular body about its centre:
TABULAR COLUMN:
No. of
oscillations
Time in
sec.
No. of
oscillations
Time in
sec.
Time for 20
oscillations
Mean
0
5
10
15
20
25
30
35
Period, =
= ---------------- sec.
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TABLE-3: To determine the radius of given wire:
Pitch of screw gauge, P =
= ---------
L.C. of screw gauge, LC =
= ---------- mm.
Zero error with sign, ZE = ____
TABULAR COLUMN:
Trial
no.
PSR in mm HSR in
division
TR=PSR+(HSR-Z)LC in mm Mean (d) in
mm
Mean radius,
= ------ = _________m.
CALCULATIONS:
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: VISCOSITY OF WATER
AIM: To determine the co-efficient of viscosity of water by capillary flow
method.
APPARATUS: Aspirator bottle with side hole, a fine capillary tube, stop
clock, measuring jar, beaker etc.
PROCEDURE: The experimental setup is made as shown in the figure. An
aspirator bottle is graduated vertically by means of a graph. A capillary tube of
length l is introduced inside the hole horizontally. The bottle is filled with water
to a considerable level. To preset the water running along the tube, a piece of
thread is tied at the end of the tube and hanging from it.
The free end of capillary is closed by the thumb and height of the water level of
the bottle is noted.
A beaker is placed just below the free end of the tube. Water is collected in the
beaker say for 5 minutes. The height of the water level in the bottle is noted.
The volume of the water ‘v’ collected in the beaker is measured using a
measuring jar.
The experiment is repeated for different time ‘t’ in seconds. Observations are
tabulated and in each case [
] are calculated. The length ‘l’ of capillary tube is
measured. The inner radius of the capillary tube is measured using vernier
calipers. The viscosity of water is calculated using the formula,
[
]
in N sec/m2.
RESULT: Viscosity of water, = ______ Nsm-2
.
Department of Physics, GFGC, Thirthahalli.
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OBSERVATIONS:
FORMULA USED:
Viscosity of water,
[
]
in N sec/m2
Where, g = acceleration due to gravity in m/s2
= density of water in Kg/m3.
r = radius of tube (inner) in m.
t = time of flow of water in sec.
h = height of water above tube in m.
v = volume of water collected in t sec in m3.
EXPERIMENTAL SET UP:
Acceleration due to gravity, g = _______m/sec2
Density of water, = _________Kg/m3.
Length of capillary tube, l = _______m.
Radius of capillary tube, r = _______m.
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TABLE-1: To find [
] :
TABULAR COLUMN:
[
]
= ______sec/m2
TABLE-2: To find the radius of the capillary tube:
TABULAR COLUMN:
Trial
no.
Reading in cm Mean diameter d in m
R1 R2 R1 R2
Mean radius,
= ------- = _________m.
CALCULATIONS:
The Coefficient of viscosity of water is,
[
]
in N sec/m2.
Trial
no.
Time
of flow
in sec
Initial height
of water h1 in
m
Final height
of water h2
in m
Mean in m
Volume of
water in
m3
[
] in
sec/m2
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: VOLUME RESONATOR
AIM: To determine the velocity of sound at lab temperature and at 00C using
volume resonator.
APPARATUS: Volume resonator, tuning fork, beaker, measuring jar, vernier
calipers, thermometer etc.
PROCEDURE: The volume resonator is set on the experimental table as
shown in the figure. Water is poured into the resonator up to the base of the
neck. A tuning fork of known frequency is set into vibration by striking it on
the rubber pad and held just above the mouth of the volume resonator
horizontally such that vibrations are parallel to the air column in the neck. Using
pinch cork little water is allowed to fall into a clean beaker till a loud resonance
sound is observed.
The volume of the water V is collected in the beaker is measured using a
measuring cylinder. The experiment is repeated for different tuning forks and
observations are noted.
A graph of f 2
verses 1/v is plotted. The slope of straight line is calculated. The
length ‘l’ of the neck of aspirator bottle is measured. Using vernier calipers, the
inner diameter ‘d’ of the neck is measured. Then the velocity of sound in air at
lab temperature is calculated using the formula,
√
m/s.
If t0C is the lab temperature then, velocity of sound at 0
0C is V0 and is
calculated using the formula, √
.
RESULT: Velocity of sound at lab temperature, V = _______ms-1
.
Velocity of sound at 00C temperature, V0 = _______ms
-1.
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OBSERVATIONS:
FORMULA USED:
(a) Area of the neck,
Where, d = inner diameter of neck in m.
(b) The velocity of sound in air at laboratory temperature,
√
m/sec.
Where, a = area of neck in m2.
l = length of neck in m.
(c) If T0 C is a lab temperature then, velocity of sound at 0
0 C is and is
calculated by the formula, √
Where, f = frequency of tuning fork in Hz.
V = volume of water collected at resonance in m3.
a = area of neck.
EXPERIMENTAL SET UP:
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NATURE OF GRAPH:
Observations:
Lab temperature, t = ____ 0 C.
Length of the neck of the bottle, l = ________ m.
Inner diameter of the neck, d = _________ m.
TABULAR COLUMN:
Trial
no.
Frequency of
tuning fork in Hz
Volume of
water v in m3
f 2 in Hz
in m
-3
CALCULATIONS:
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: SURFACE TENSION BY DROP WEIGHT METHOD
AIM: To determine surface tension of water by drop weight method.
APPARATUS: Funnel glass tube, rubber tube, pinch cork, beaker, water,
physical balance, weight box, stop clock etc.
PROCEDURE: The experimental setup is made as shown in the figure. Water
is filled in the funnel by releasing the pinch cork. The air bubbles are removed
which are present in the rubber tube and glass tube.
The pinch cork is tightened and is now adjusted such that about to 8 to 10 drops
are formed at the end of the glass tube per minute. With this adjustment, 30
drops of water are collected in a clean dry weighted beaker.
The beaker with collected water is weighed again. From these observations, the
weight of single drop is calculated. Using screw gauge, the external diameter of
the glass tube at which the drops are formed is determined. Then the surface
tension ‘T’ of water is calculated using the formula,
in Nm
-1. Where, r
is the outer radius of glass tube.
RESULT: Surface tension of water, T = _______Nm-1
.
Department of Physics, GFGC, Thirthahalli.
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OBSERVATIONS:
FORMULA USED:
Surface tension ‘T’ of water,
in Nm
-1
Where, g = acceleration due to gravity in ms-2
.
m = mass of single drop formed in air in kg.
r = the outer radius of glass tube in m.
EXPERIMENTAL SET UP:
TABLE-1: To find the mass of a single water drop:
TABULAR COLUMN:
Mass of dry
beaker, m1 in
Kg
Mass of beaker + 30
drops of water, m2 in
Kg
Mass of 30 drops
of water, (m2- m1)
in Kg
Mass of single drop,
in Kg
Mass of a single water drop, m = _________ Kg.
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Table-2: To find the outer radius of the glass tube using screw gauge:
Pitch of screw gauge, P =
= --------- mm.
L.C. of screw gauge, LC =
= ---------- mm.
Zero error with sign, Z = ____
TABULAR COLUMN:
Trial
no.
PSR in mm HSR in
division
TR=PSR+(HSR-Z)LC in mm Mean (d) in
mm
Mean diameter, d= ________mm.
Radius,
= ---- = _________m
CALCULATIONS:
Department of Physics, GFGC, Thirthahalli.
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Expt. Name: SURFACE TENSION OF WATER BY CAPILLARY RISE
METHOD
AIM: To determine surface tension of water by capillary rise method.
APPARATUS: Capillary tube, small beaker, pure water, travelling
microscope, a pin etc.
PROCEDURE: A small beaker containing sufficient water where surface
tension is to be measured is placed on the screw motion adjusted stand.
Capillary tube is held vertically by a stand in such a way that, its lower end is
dipped in the water. A pin is attached to the capillary tube and the stand is
adjusted such that the tip of the pin just touches the surface of water in a beaker.
Due to the surface tension, water raises to a certain height in the capillary tube.
Care is taken to see that, there is no air bubble inside the capillary tube. The
arrangement may be examined with an electrical bulb.
A travelling microscope is arranged in front of the capillary tube. The
microscope is focused such that the horizontal cross wire is made to coincide
with the image of the upper meniscus of water in the capillary tube. The stand
is lowered and beaker with water is removed. The microscope is lowered and is
focused to the tip of the pin and readings are noted. The experiment is repeated
and average height of water in the capillary tube is noted.
The capillary tube is held horizontally. The microscope is focused to the free
end of the tip and the internal diameter and hence internal radius of the capillary
tube is measured.
Observations are tabulated as shown. The surface tension of the water is
calculated using the formula,
[
]
RESULT: Surface tension of water, T = _______Nm-1
.
Department of Physics, GFGC, Thirthahalli.
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OBSERVATIONS:
FORMULA USED: Surface tension of the water,
[
]
Where, g = acceleration due to gravity in m/s2.
d = density of water in Kgm-3
= _______ Kgm-3
r = inner radius of the capillary of the capillary tube in m.
h = capillary rise in m.
EXPERIMENTAL SET UP:
TABLE-1: To determine capillary rise:
L.C. of travelling microscope, L.C. =
= -------- cm.
TABULAR COLUMN:
Trial
no.
Reading of the
meniscus h1 in cm
Reading against tip of the
pin h2 in cm
Capillary rise h1-h2
in cm
Mean, h = __________ m
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TABLE-1: To determine the inner radius of the tube:
TABULAR COLUMN:
Position Reading in cm Mean diameter in
cm
Radius in cm
Rl R
ll R
l - R
ll
Horizontal
Vertical
CALCULATIONS: