Diagram
1
Measuring Instruments
Screw Gauge
Aim
To measure the diameter of a thin wire.
Apparatus Required:
Screw gauge and the given wire.
Description:
The screw gauge consists of a U- shaped frame – F having a fixed stud A at one end and a barrel C
attached to the other end. A screw „B‟ of uniform pitch passes through one end of the frame and
the barrel. A millimetre scale is engraved o the barrel along its length. This is called Pitch Scale. The
screw carries a head H which has an edge „S‟ with 100 divisions. This is called Head Scale. When
the head is rotated the head scale moves on the pitch scale.
(i)
To find the least count
To find the least count, pitch is to be determined first.
Pitch = Number of divisions moved by the head on the Pitch Scale / Number of rotations
given to the head scale.
To find the pitch the head is given say 5 rotations and the distance moved by the head on the
pitch scale in noted.
Pitch
=
= 1 mm
Least Count =
=
(ii)
= 0.01 mm
To find zero error
To find zero error, the stud A and screw tip B are kept in contact.
If the zero of the head scale coincides with the zero of the pitch scale on the reference line,
the instrument is said to have no zero error (fig. b)
2
To find the radius of the wire using screw gauge
Z.E = ------- div
S.No PSR x10-3 m
Z.C = ------ div
HSC
(div)
CHSC=HSC
±Z.C (div)
LC = 0.01 mm
HSR = (CHSC x Total Reading =(PSR+
LC ) x10-3 m
HSR ) x 10-3 m
1
2
3
4
5
CALCULATIONS
3
(a)
Positiv
e zero error
If the zero of the head scale lies below the reference line of the pitch scale, the zero error is
positive and the correction is negative.
(b)
Negati
ve zero error
If the zero of the head scale lies above the reference line of the pitch scale (fig d ) the zero
error is negative and the correction is positive.
Result:
The thickness of the given material is found to be ------------------------
4
Diagram
Fig .a. Vernier Caliper
5
Vernier caliper
Aim:
To measure the external and internal diameters of a given hollow cylinder.
Apparatus Required:
A vernier caliper and a hollow cylinder
Description:
The vernier caliper shown in the Fig. a consists of a long steel strip. One end of the steel strip is
divided into 1/10 of centimeter (1mm) .
A fixed jaw „A‟ is attached to one end of the steel strip. A movable jaw „B‟ which can freely move
on the steel strip has a vernier scale marked on it. The jaw „B‟ can be fixed at any point by means of
a screw S. The two jaws can be brought together and closed without a gap. The vernier scale is
divided into 10 divisions which is equivalent to 9 main scale divisions. Hence the value of 1 vernier
scale division (VSD) is equal to 9/10 main scale division (MSD). The value of 1 main scale divisions
is 1mm.
Least count:
It is the smallest length that can be measured by the vernier caliper. It is the difference between one
main scale division and one vernier scale divisions.
Least count = 1MSD-1VSD
= 1 MSD-9/10MSD
= 1/10 MSD
= 1/10 x0.1cm=0.01 cm(since 1 MSD= 1mm= 0.1 cm)
Zero Error:
If the zero of vernier scale coincides with the zero of the main scale when the two jaws are kept
closer, the instrument is said to have no zero error. (Fig.b)
6
To find the diameter of the metallic disc using vernier calipers.
S.NO
MSR X 10-2 m
VSC(div)
VSR= VSC X LC
Total reading= (MSR+VSR) X
X 10-2m
10-2 m
1.
2.
3
4.
5.
CALCULATIONS
7
Positive zero Error:
If the zero of the vernier scale lies on the right side of the zero of the Main scale, then the instrument
has an error called positive zero error. (Fig.c). This error is to subtracted from the final reading i.e.,
the zero correction is negative.
Negative zero Error:
If the zero of the vernier lies on the left side of the zero of main scale, then the instrument is said to
have an error called negative zero error. (fig.d). this error is to be added to the final reading. i.e., the
zero correction is done.
Result:
The diameter of the given material is found to be ---------------
8
Diagram
Fig.a.Spectrometer
Fig .b. Spectrometer readings
9
SPECTROMETER
Aim:
To study the functions of different parts of a spectrometer and their adjustments
Description:
The collimator is an arrangement for producing a parallel beam of light. It consists of a hollow brass
tune with a vertical slit (S), at one end and a Collimating Lens (L) at the other end. To obtain parallel
beam of rays, the distance between the slit and lens has to be adjusted. This can be done by means of
a side screw attached to the collimator. The width of the slit can be adjusted by a screw attached to
its side. The collimator is a fixed one and it cannot be rotated.
Telescope:
The telescope is attached to a circular scale graduated in degrees. It can be rotated about a circular
axis passing through the centre of the circular scale.
It has an objective O near the collimator ad an eye piece E at the other end. The eye piece of the
telescope is provided with crosswire. The focusing of the telescope is done by a screw attached to the
side of the telescope.
The telescope can be rotated and fixed at any position using a ain screw. The telescope can be rotated
by very small amounts by a fine adjustments screw which is tangential to the main screw.
Prism table
The prism table consists of two identical metal discs separated by three springs. Through the springs
pass three levelling screws. The top surface of the upper disc contains lines to mount the prism in
proper position. The prisms table can be raised or lowered and fixed at an desired height by means of
a screw. The prism table can be rotated about the same vertical axis as the telescope.
A vernier disc attached to vertical axis carries two diametrically opposite vernier scales V A and VB .
The vernier disc can be rotated and fixed at any position by a main screw and a fine screw as in the
telescope.
10
11
Procedure
Initial adjustments:
Eye piece: The telescope is turned towards a white wall and the eye piece alone is adjusted until the
cross wires are clearly seen.
Telescope: The telescope is turned towards a distant object. The distance between the eyepiece and
objective is adjusted by the screw until a clear image is seen on the crosswire.
Collimator: The slit of collimator is illuminated by sodium light. The slit is adjusted fine and
narrow. The distance between the slit and the collimating lens is adjusted so that clear image is got
on the cross wire when the telescope is brought in line with the collimator.
Prism table: The prism table is made horizontal using a spirit level. The spirit level is placed on the
prism table along the line joining any two legs. Then the leveling screws of the prism table alone are
adjusted until the air bubble comes to the centre. The process is repeated by keeping the spirit level at
different places until the prism table is exactly horizontal.
To find least count:
The value of each main scale division is half degree(=30). The number of vernier scale divisions is
30.29 main scale divisions are divided into 30 vernier scale divisions(ie 30VSD = 29MSD).
Therefore value of 1 VSD= 29/30 MSD. It is known that the least count is the difference between 1
MSD and 1VSD.
Least count(LC) = 1MSD – 1VSD
= 1MSD – 29/30 MSD
= 1/30 MSD = 1/30 x 30‟ =1‟
Least count
= 1‟ (one minute)
To read the readings
During experimentation readings must be taken from both vernier A and vernier B scales and
tabulated. Fig. b shows the typical reading observed in vernier A and vernier B. since vernier A and
vernier B are at diametrically opposite places in the circular vernier disc, in a perfect instrument the
difference between these readings must be 1800
12
DIAGRAM
Torsional Pendulum
TABULAR COLUMN:
TABLE 1 : To find the period of oscillation (T) & L/T2
Time for
Time for 10
Length of the suspended wire (L)
S.No
oscillations (sec)
(cm)
Trial 1
Trial 2
Mean
one
(sec)
oscillation
L/T2m/s2
(T)sec
13
TORSIONAL PENDULUM
Expt No :
Date :
AIM:
To determine the rigidity modulus of the given wire and moment of inertia of the disc by Torsional
pendulum (withour masses).
APPARATUS REQUIRED:
Circular metallic disc, suspended wire, meter scale, stop clock, screw gauge etc
FORMULAS USED:
MR 2
Moment of inertia of the disc I =
Kg m2
2
Rigidity modulus of the material of the wire n =
8IL
r 4T 2
N/m2
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit
M
Mass of the circular disc
kg
R
Radius of the circular disc
meter
r
Radius of the given wire
meter
L
Length of the suspended wire
meter
T
Time period for various lengths
second
PROCEDURE:
Uniform thin wire whose rigidity modulus has to be found is suspended from a rigid support. The
other end of the wire is attached to a circular disc (for which moment of inertia is to be determined)
using an adjustable chuck. The length of the wire is noted. A small twist is given to the disc, to that it
exhibits torsional oscillations. The time taken for 10 oscillations is noted. From this the time period
of oscillation is found out. The length of the wire is now increased by
14
TABLE 2 : To find the radius of the wire using screw gauge
LC = 0.01mm
Zero Error Z.E = ---------- div
S
PSR x
NO
-3
10 m
HSC (div)
CHSC = HSC ±
Z.C (div)
Z.C = ----- div
HSR = (CHSC x
-3
LC) x 10 m
Total Reading = (PSR
+ HSR)x
10-3m
1
2
3
4
5
CALCULATIONS
15
5cm and the same procedure is repeated, for various values of L. The mean value of L/T2 is
calculated. The mass of the disc is found using a rough balance. The circumference of the disc is
found using a thread, from which the radius of the disc is calculated. From these values the moment
of inertia and the rigidity modulus can be found out.
RESULT: .
The Rigidity Modulus of the material of the given beam is = --------------------The Moment of Inertia of the disc is = ----------------
16
DIAGRAM
17
LASER GRATING
Expt No :
Date :
AIM:
To determine the wave length of the given laser source using grating
APPARATUS REQUIRED:
A laser source, grating, meter scale, etc.,
FORMULA :
Wave length of the laser source  =
sin 
Nm
Å
x
 deg
D
 = tan-1 
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit

Wave length of the laser source
Nm

Angle of diffraction
Degrees
x
Distance between the center and the diffracted
meter
images
D
Distance between the central spot and the grating
meter
N
Number of lines in the grating
-----
m
Order of the diffracted images
----
18
19
PROCEDURE:
The grating is placed in front of the laser source using a stand. As soon as the source is switched on
diffracted images are formed in the screen due to diffraction. The pattern consists of a central spot
and diffracted images on either side. The distance between the central spot and the grating is noted as
(D). The distance between the central spot and each diffracted images are noted on either sides as (x).
Using the above relations the wavelength of the given laser source is determined.
20
CALCULATIONS
21
RESULT: .
The wave length of the given laser source is = -----------------------22
DIAGRAM
Lee’s Disc
Sample graph
23
LEE’S DISC METHOD
Expt No :
Date :
AIM:
To determine the thermal conductivity of the given bad conductor by Lee‟s disc method.
APPARATUS REQUIRED:
Lees disc apparatus, two thermometers, bad conductor, screw gauge, vernier calipers,
stop clock etc.,
FORMULA :
Thermal conductivity of the bad conductor is
K
 d 
MS   xr  2h 
dt
= 2   2
r 1   2 2r  h 
W/m/K
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit
M
Mass of the metallic disc
kg
S
Specific heat capacity of the material of the disc
J/kg/K
1
Steady temperature of the steam chamber
Degrees
2
Steady temperature of the metallic disc
Degrees
r
Radius of metallic disc
meter
h
Thickness of the metallic disc
meter
x
Thickness of the bad conductor
meter
24
TABULAR COLUMN:
Table 1 : Time Vs Temperature
Temperature (deg)
Time (seconds)
Table 2 : To find the diameter of the metallic disc using vernier calipers
Z.E = -------- div
S.No
Z.C = -----------div
MSR x
VSC
VSR = VSC x LC x
-2
(div)
10-2m
10 m
L.C = 0.01 cm
Total Reading = MSR + VSR x 10-2m
1
2
3
4
5
25
PROCEDURE:
The bad conductor is placed in between the steam chamber and the metallic disc. The steam chamber
is connected to steam and a thermometer is inserted to note the steady temperature. Another
thermometer is mounted on the metallic disc. Steam is allowed to pass through. Due to thermal
conductivity of the bad conductor, the metallic disc shows rise in temperature. The system is
maintained as such till the metallic disc attains a steady temperature. The steady temperatures are
noted down. Now the bad conductor is removed and the metallic disc is made to contact the steam
chamber directly. Now the temperature of the metallic disc rises above its
steady temperature. Allow it to rise. Then disconnect the steam chamber. After sometime the metallic
disc shows decrease in its temperature. Now start a stopwatch and note the time for every one degree
fall in temperature from 2+5 to 2-5. A graph between time and temperature is drawn from which
d/dt at 2 is noted. The thickness of the metallic disc and the bad conductor is found using screw
gauge and the diameter of the metallic disc is found using vernier calipers. With all these data the
thermal conductivity of the bad conductor if found out.
26
Table 3 : To find the thickness of the metallic disc by screw gauge
Z. E = -------- div
PSR x 10-3 m
S
Z.C = ---------- div
LC = 0.01mm
HSC
CHSC = HSC
HSR = CHSC x LC x
Total Reading = (PSR +
(div)
± Z.C (div)
10-3m
HSR) x 10-3m
….
1
N.N
2
.No.
3
No
4
5
Table 4 :To find the thickness of the bad conductor using screw gauge
Z. E = -------- div
S
NO
PSR x 10-2m
Z.C = -------- div
HSC (div)
LC = 0.01mm
CHSC = HSC ±
HSR = CHSC x LC
Total Reading = (PSR
Z.C (div)
x
+ HSR)x 10-3m
10-3m
1
2
3
4
5
27
28
CALCULATIONS
29
RESULT: .
The thermal conductivity of the bad conductor is = ----------------------------
30
DIAGRAM
Poiseuille’s Method
31
POISEUILLE’S METHOD
Expt No :
Date :
AIM:
To determine the coefficient of viscosity of the given liquid by Poiseiulle‟s method.
APPARATUS REQUIRED:
A graduated burette, rubber tube, capillary tube, pinch cork etc.,
FORMULA :
gr 4  ht 
-2
Coefficient of viscosity =  =
  Nsm
8l  V 
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit

Density of the given liquid
kg /m3
g
Acceleration due to gravity
m/s2
r
Radius of the capillary tube
meter
l
Length of the capillary tube
meter
h
Driving height of the liquid level
meter
t
Time taken for a known height of liquid to flow
Seconds
V
Volume of the liquid
m3
PROCEDURE:
The burette is filled with the given liquid. A capillary tube is attached to the lower end of the burette
using a rubber tube. The capillary tube is made vertical and the liquid is allowed to flow through it.
When the liquid comes to a known height (h1), height measured from the axis of the capillary tube,
the stopwatch is started. The stopwatch is stopped when the liquid flows to another level (h2). The
driving height is given by h = ((h1 + h2) / 2) – h0, where h0 is the height of the center of the capillary
tube from table. (Since h1 and h2 are measured from table and driving height is with respect to the
capillary tube, the term h0 is incorporated in the formula for driving height. The volume of the liquid
32
TABULAR COLUMN:
TABLE 1 : To find (ht/V)
S. No
Range
Volume x 10-6
Time of
(Burette)
m3
flow(sec)
h1 x
10-2 m
h2 x
10-2 m
h=(
h0
-2
10 m
ht/V
sec/ m2
Reading)
0 –5
5 – 10
ho
10 – 15
= ---------
15 – 20
x 10-2 m
S.
No
(sec)
20 – 25
25 – 30
30 – 35
35 – 40
40 – 45
45 – 50
CALCULATIONS
33
and time of flow are noted. Using the above formula the coefficient of viscosity of the given liquid
can be calculated. The radius of the capillary tube will be given.
RESULT
The coefficient of viscosity of the given liquid is = ------------------------
34
DIAGRAM
Angle of Prism
Angle of minimum deviation
35
SPECTROMETER
Expt No :
Date :
AIM:
To determine the refractive index of the material of the prism
APPARATUS REQUIRED:
A source, prism, reading lens etc.,
FORMULA :
Refractive index of the material of the prism
μ
=
 A D
sin 

 2  (no units)
 A
sin  
2
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit
A
Angle of the prism
degrees.
D
Angle of minimum deviation
degrees
PROCEDURE:
The initial adjustments of the spectrometer are made. The prism is placed on the prism table and is
illuminated by a sodium vapour lamp. The prism is placed in such a way that its base is parallel to
the collimator. The deviated ray is found by moving the telescope towards the base of the prism and
the prism table is rotated such that the slit moves in a particular direction (ie towards the direct ray),
stops and retraces its path. This position is found out and the slit is made to coincide with the cross
wire and readings are noted, from which angle of deviation is determined. Assuming the value of the
angle of Prism
(A = 60ο) the values the refractive index of the material of the prism is found out.
36
TABULAR COLUMN:
To Find Angle of Minimum Deviation
Position
Vernier A
MSR
VSC
deg
div
VSR =
VSC x LC
Vernier B
TR
MSR
VSC
deg
deg
div
VSR = VSC
x LC
TR
deg
Deviated Ray
Direct Ray
CALCULATIONS
37
RESULT: .
The refractive index of the material of the prism is = -----------------------38
DIAGRAM
39
SPECTROMETER GRATING
Expt No :
Date :
AIM:
To determine the wavelength of colours in the mercury spectrum using grating .
APPARATUS REQUIRED:
Spectrometer, plane transmission grating, mercury vapour lamp, spirit level etc.,
FORMULA :
Wavelength of the prominent lines of the mercury spectrum is
λ =
sin 
Nn
A0
EXPLANATION OF SYMBOLS:
Symbol
Explanation
Unit
n
Order of the spectrum
-

Wave length of the prominent lines of the mercury spectrum
A0

Angle of diffraction
degree
N
Number of lines in the grating
PROCEDURE:
The initial adjustments of the spectrometer are made. The given grating is mounted on the
spectrometer table using the grating mount. The spectrometer is placed in front of the mercury
Vapour lamp. The verniers are made to read 0ο and
180ο
the telescope is rotated through 90
degrees. Then the prism table is rotated till the image of the white is seen through the telescope. This
is then made to coincide with the cross wire. Now the vernier table is rotated through 45 degrees in
anticlockwise direction. Now the grating is said to be adjusted for normal incidence. Then the
telescope is brought back to initial position. A central white image with spectrum on either is
obtained.The diffracted images of the first order of various colors are seen on either sides of the
central white image. The telescope is moved on one side and the vertical cross wire is made to
coincide with the green colour. The reading on vernier A & B is noted. Similarly
40
41
readings are taken for green colour on the other side. The same procedure is repeated for other
colours also and readings are tabulated .Then mean angle of diffraction is found out, from which
wavelength of colours can be calculated.
RESULT: .
The wavelength of various colours of the mercury spectrum was found to be -----
42
CIRCUIT DIAGRAM
SAMPLE GRAPH
43
TRANSISTOR CHARACTERISTICS
Expt No :
Date :
AIM:
To study the Common Emitter characteristics for the given transistor.
APPARATUS REQUIRED
Bread Board, Transistor, eliminator, ammeter (milli ammeter and micro ammeter),
voltmeter
Formula:
 dVBE
 dI B
Input Resisitance Ri = 
Output Resistance Ro =
Current Gain β =
 dI C

 dI B

 Ω
VCE
 dVCE

 dI C


 VCE


 IB
Ω
No unit
Expansion of the symbols:
Symbol
Explanation
Unit
dVBE
Small change in base emitter voltage
Volt
dVCE
small change in collector emitter voltage
Volt
dIB
small change in base (Input) Current
Ampere
dIC
Small Change in Collector (Output) Current
Ampere
44
TABULAR COLUMN
INPUT CHARACTERISTICS
S . No
VCE
VCE (V)
(V) =
VBE (V)
IB (μA)
VBE (V)
=
IB (μA)
OUTPUT CHARACTERISTICS
S.No
IB (μA) =
VCE (V)
IB
IC (mA)
VCE (V)
(μA) =
IC (mA)
45
PROCEDURE:
Electrical Connections are made as shown in the figure.
To study the input characteristics, collector emitter voltage is kept constant and the variation
of base current with respect to input voltage (VBE) is noted. The procedure is repeated for different
values of VCE.
To obtain output characteristics, the changes in collector current (IC) with respect to collector
emitter voltage (VCE) for various values of base current (IB) are measured.
To determine the gain (β) of the transistor VCE should be kept constant and IB is varied and
corresponding collector current (IC) is noted.
With all these, graphs for input, output and gain characteristics are drawn.
46
GAIN
S.No
VCE =
IB (μA)
v
IC (mA)
CALCULATIONS
47
RESULT: .
The transistor characteristics in common emitter configuration were drawn and studied.
Input Resistance = -----------------Output Resistance = ----------------Current gain = -----------------------------
48
DIAGRAM
Fig. a. Air wedge Apparatus
49
AIR WEDGE
Expt No :
Date :
AIM:
To determine the thickness of the given wire by forming air wedge.
APPARATUS REQUIRED:
Sodium Vapour Lamp, Glass Plates, Traveling Microscope.
FORMULAS USED:
Thickness of the wire
t=
l
m
2
Expansion of the symbols:
Symbol
Explanation
Unit
β
Fringe width
metres
λ
Wavelength of the monochromatic light
metres
l
Distance between angle of inclination and the material for
metres
which thickness is to be determined
50
TABULAR COLUMN:
Table 1: To find the fringe width
L.C = 0.001cm
Microscopic reading
Order of the
fringes
MSR
10-2 m
VSR =
VSCxL.C
10-2 m
Width of 5
Fringe width
TR
fringes
()
10-2 m
10-2 m
10-2 m
n
n+5
n+10
n+15
n+20
n+25
n+30
n+35
n+40
n+45
n+50
51
PROCEDURE:
Two glass plates are joined together put a rubber band on one end. On the other end the given
wire is placed. This setup now acts as air wedge. This is illuminated by sodium light, interference
occurs between the two rays, one reflected from the front surface and the other obtained by internal
reflection at the back surface. Light from the sodium vapour lamp, is rendered parallel by means of a
condensing lens. The parallel beam of light is incident on a plane glass plate, inclined at an angle of
450 and gets reflected. The reflected light is incident normally on the glass plates. The interference
pattern is viewed through a traveling microscope. Large number of equally spaced dark and bright
fringes are formed in the field of view. The microscope is adjusted so that the vertical cross wire
coincides with one of the dark fringe. The reading from the horizontal scale is noted. Now the
microscope is moved across the fringes using horizontal traverse screw, so that it coincides with n+5
th fringe. The readings are noted. This is followed till we come to n+50 fringes. The width for 20
fringes is found out, from which fringe width can be calculated. The cross wire is fixed at the inner
edge of the rubber band. Reading are noted. Then it is made to coincide with wire and readings are
taken. Difference between these two readings gives the distance between the wire and rubber band.
Substituting all the above values, the thickness of the wire is calculated.
52
Table 2 : To find the distance between wire and the edge of the rubber band
LC =0.001 cm
Microscopic reading
Position of the
microscope
l = R1 ~ R2
MSR
VSR = VSCxL.C
TR
10-2 m
10-2 m
10-2 m
10-2 m
At the edge of
the contact
(R1)
At the edge of
the material of
(R2)
the wire
CALCULATIONS:
53
RESULT:
The thickness of the given wire by forming air wedge is found to be ……………...
54
DIAGRAM
TABULAR COLUMN:
Sl.No
Distance between
Order of
Distance between the
Particle size
the screen and the
Diffraction
central bright point
glass plate D (cm)
n.
and nth fringe (xn) (cm)
2d =
cm
1
1
2
3
4
2
1
2
3
4
Mean = ..............x10-2m
55
PARTICLE SIZE DETERMINATION BY LASER
Expt No :
Date :
AIM:
To determine the particle size of the given lycopodium powder using laser diffraction method.
APPARATUS REQUIRED:
He-Ne laser or semiconductor laser, Lycopodium powder, Glass plate, Screen.
FORMULAS USED:
Grain size (diameter) „2d‟ of the given particle
2d =
metre
Expansion of the symbols:
Symbol
Explanation
Unit
D
Distance between the screen and glass plate
metres
Λ
Wavelength of Helium-Neon laser
metres
xn
Distance between the central bright point and nth fringe (xn)
metres
(cm)
n
Order of rings
56
CALCULATIONS:
57
PROCEDURE:
The powder of few microns whose size is to be determined is spread over the glass plate. The glass
plate is inserted vertically through the path of the laser beam. To get the contrast circular rings on the
screen the glass plate is adjusted until clear image is formed. After the ring formation using white
paper or trace sheet the circular patterns are marked carefully. The ratio of different order dark rings
(xn) are measured. The distance between the screen and the glass plate is D is measured. Knowing
all, the size of particle can be calculated. Using the formula the particle size can be found for
different D value
RESULT:
Average size of the particle = ................10-2m
58
DIAGRAM
Steam generator
Copper calorimeter
59
THERMAL CONDUCTIVITY OF THE GIVEN RUBBER TUBE
Expt No :
Date :
AIM:
To determine the thermal conductivity of the given rubber tube.
APPARATUS:
A Steam Generator, a Copper Calorimeter Rubber Tubing, A Thermometer, Access To A Balance (±
0.1 Gm), A Stopwatch
FORMULA USED :
Thermal conductivity of Rubber tube is given by
x
Wm-1K-1
Expansion of the symbols:
Symbol
Explanation
Unit
c1
Specific heat capacity of Calorimeter
J/kg/K-1
C
Specific heat capacity of Water
J/kg/K-1
θ3
Initial temperature of water
degree
θ4
Final temperature of water
degree
w1
Weight of empty calorimeter
kg
w2
Weight of Calorimeter with water
kg
l
Length of the rubber tube beneath the water surface
metre
r1
Inner radius of the rubber tube
metre
r2
Outer radius of rubber tube
metre
θ1
Steam temperature
degree
t
Time taken to pass the steam through the tube
sec
60
Readings are tabulated as follows:
Mass of the empty calorimeter and stirrer (w1) = ………
Mass of the empty calorimeter + two-thirds water (w2) = …….
Initial temperature of the water (θ3 °C) = ……………….
Final temperature of water in Calorimeter (θ4 °C). =
Time for which steam is passed t seconds = ……….
Length of rubber tube immersed in water , l = …………..
Internal radius of the rubber tube r1 = ………
External radius of the rubber tube r2 = …………
Steam temperature (θ1°C) may be taken as 100°C
CALCULATIONS:
61
PROCEDURE :
A large calorimeter of capacity 500 ml is weighed empty, with stirrer (w1). It is filled two-thirds with
cold water at room temperature and again weighed (w2).
A known length (l) of rubber tube is coiled and immersed in water contained in the calorimeter, with
both ends of the tube projecting some distance outside the calorimeter. The length of the rubber
tubing kept immersed in water is indicated by two fine strings tied round the tube where it just
merges out of the water.
The water in the calorimeter is stirred well and the initial temperature θ3°C is noted. Now, one end
of the rubber tube is connected to the steam generator, and steam is passed through it, at once starting
a stop clock. The calorimeter is kept stirred well and the temperature is noted with a thermometer
kept immersed in it. The steam is passed continuously till there is a rise of 10°C in temperature. The
time (t seconds) taken for this rise in temperature is noted.
Temperatures are noted every 30 sec from the beginning even after the steam is cut off, until there is
a fall in temp of 1°C.
Let θ4 be the final temperature of the water in the calorimeter. The external diameter of the rubber
tube is determined by measuring with a screw gauge at several places. In order to find the internal
radius r1, a known length of the rubber tube is immersed measuring cylinder containing water, and
its volume V is determined. If r2 is the external radius of the tube. V = π(r22 - r12 ) from which r1 is
calculated. From these thermal conductivity of rubber is determined
Result :
The thermal conductivity of the given rubber tube is found to be = ………
62
DIAGRAM
Fig. (1) - Forward Bias Condition
Fig. (2) - Reverse Bias Condition:
Fig(3) V- I Characteristics of PN Junction Diode under Forward & Reverse Bias Conditions
63
DIODE CHARACTERISTICS
Expt No :
Date :
AIM :
To observe and draw the Forward and Reverse bias V-I Characteristics of a P-N Junction
diode.
APPARATUS:P-N Diode IN4007, Regulated Power supply (0-30 V), Resistor 1KΩ, Ammeters (0-200 mA, 0500mA), Voltmeter (0-20 V), Bread board, Connecting wires
Diode current equation
The volt-ampere characteristics of a diode explained by the following equations:
Expansion of the symbols:
Explanation
Unit
Symbol
I
current flowing in the diode,
mA
I0
reverse saturation current
µA
V
Voltage applied to the
volts
diode
VT
volt- equivalent of temperature
volts
=1 (for Ge) and 2 (for Si)
PROCEDURE:FORWARD BIAS:1. Connections are made as per the circuit diagram.
2. For forward bias, the RPS +ve is connected to the anode of the diode and
RPS –ve
is
64
TABULAR COLUMN
1. Forward Bias
S.NO APPLIED VOLTAGE
(V)
VOLTAGE ACROSS
CURRENT
DIODE(V)
DIODE(mA)
THROUGH
2.Reverse Bias
S.NO APPLIED VOLTAGE
(V)
VOLTAGE
DIODE(V)
ACROSS
CURRENT THROUGH
DIODE(µA)
65
connected to the cathode of the diode,
3. Switch on the power supply and increases the input voltage (supply voltage) in steps.
4. Note down the corresponding current flowing through the diode and voltage across the
diode for each and every step of the input voltage.
5. The reading of voltage and current are tabulated.
6. Graph is plotted between voltage and current.
It is observed that Ge diodes has smaller cut-in-voltage when compared to Si diode. The reverse saturation
current in Ge diode is larger in magnitude when compared to silicon diode.
REVERSE BIAS:1. Connections are made as per the circuit diagram
2 . For reverse bias, the RPS +ve is connected to the cathode of the diode and RPS –ve is
connected to the anode of the diode.
3. Switch on the power supply and increase the input voltage (supply voltage) in Steps
4. Note down the corresponding current flowing through the diode voltage across the diode for
each and every step of the input voltage.
5. The readings of voltage and current are tabulated
6. Graph is plotted between voltage and current.
66
67
RESULT :
Forward and Reverse Bias characteristics for a p-n junction diode is observed
68
Diagram
69
HYSTERESIS – B H CURVE – LOSS DETERMINATION.
Expt No :
Date :
AIM:
To trace the B-H curve for a ferromagnetic material using CRO and to find the hysteresis loss of a
ferromagnetic material
APPARATUS REQUIRED:
CRO, Step Down Transformer, A.C Ammeter, Rheostat, Resistant 1Ω-2nos, 47k Ω-1nos, 20 K Ω
And 5 K Ω Variable Resistances, Two Capacitors (1μf And 2μf), Solenoid, Specimen Rod.
FORMULAS USED:
Hysteresis loss =
J/Cycle/Volume
Expansion of the symbols:
Symbol
Explanation
Unit
Np
Number of turns in the solenoid,
turns
V
The voltage applied to the B-H curve apparatus
volts
R
Resistance in integrator circuit
ohms
r
Radius of the coil
metre
Lx
Maximum deflection in x-axis
metre
Ly
The length of the line along y-axis
metre
70
CALCULATIONS:
Number of turns in the solenoid
Np = ………… turns
The voltage applied to the B-H curve apparatus
V = …………. volts
Resistance in integrator circuit
R = …………. ohms
Radius of the coil
r = ……………m
Maximum deflection in x-axis
Lx = …………. m
Ly = ………… m
The length of the line along y-axis
Hysteresis loss =
X(
J/Cycle/Volume
71
PROCEDURE:
Draw a diagram showing the scheme of connections as shown in diagram and make all the
connections properly. The specimen is taken in the form of ferromagnetic rods. A solenoid is
wounded on a non-metallic frame. A centrally situated secondary of nearly 1000 turns is wound on a
spool. The specimen rod is inserted into the solenoid completely. Switch On and A.C main and
obtain maximum current in the primary circuit with the help of a rheostat Rh. Now adjust the X and
Y amplifier and so that we get a pattern within the screen. The pattern obtain should be as shown in
figure. After getting proper hysteresis pattern on the screen, place a tracing paper on screen and trace
the B-H hysteresis loop and Lx and Ly are measured. Now, slowly move the specimen rod out of the
solenoid until the length Ly of the vertical line is reduced to Ly/2. Keeping the specimen rod in this
position, adjust the y-amplifier gain to increase the length of the line to its original value Ly. This
implies that Y-amplifier gain is now double of its original value. All these values are substituted in
the equation given the hysteresis loss can be calculated.
RESULT:
Hysteresis loss = ……………………. J/Cycle/Volume
72
73
ULTRASONICS – COMPRESSIBILITY OF SOLIDS & LIQUIDS
Expt No :
Date :
AIM:
To determine the velocity of the ultrasonic waves in the given liquid and its Compressibility
by using ultrasonic interferometer
APPARATUS REQUIRED:
Ultrasonic Interferometer, Sample solid, Sample liquid
FORMULAS USED:
Wavelength of the ultrasonic wave in the medium
Velocity of ultrasonic wave in medium
Compressibility of medium
Expansion of the symbols:
Symbol
Explanation
Unit
d
Distance traversed in micrometer
metre
γ
Frequency of ultrasonic waves in the medium
hertz
λ
Wavelength of ultrasonic waves in medium
metre
n
Order of deflection in micrometer
74
TABULAR COLUMN:
Order of
Micrometer reading for n
Distance traversed
deflection
maximum deflections
in micrometer ‘d’
-3
in
micrometer
10 m
PSR
-3
10 m
HSC
TR = PSR +
div
(HSCxLC) 10-3m
λ=2d/n
V= λ
10-3m
m/s
n=5
n=10
n=15
n=20
n=25
CALCULATIONS:
75
PROCEDURE:
Ultrasonic interferometer is simple and direct device with a high degree of accuracy. It is highly
sensitive equipment and at most care should be taken in handling the apparatus.
The ultrasonic interferometer consists of the following parts
a. The high frequency generator
b. The measuring cell
High Frequency Generator is designed to excite the quartz crystal fixed at the bottom of the
measuring cell at its resonant frequency to generate ultrasonic waves in the experimental liquid
filled in the “Measuring Cell”. A micrometer to observe the changes in current and two controls
for the purpose of sensitivity regulation and initial adjustment of the micrometer is provided on
the panel of the High Frequency Generator.
The Measuring Cell is specially designed double walled cell for maintaining the temperature of
the liquid constant during the experiment. A fine micrometer screw has been provided at the top,
which can lower or raise the reflector plate in the liquid in the cell through a known distance. It
has a quartz crystal fixed at its bottom.
Initial Adjustment
1. Insert the cell in the square base socket and clamp it with the help of a screw provided on one
of its side.
2. Unscrew the knurled cap of cell and lift it away from the double walled construction of the
cell. In the middle portion of it pour experimental liquid and screw the knurled cap.
3. Two chutes in double wall construction are provided for water circulation to maintain the
desired temperature.
4. Connect the High Frequency Generator with cell by co-axial cable provided with the
instrument.
5. In Multi frequency Ultrasonic Interferometer frequency selector knob should be positioned at
desired frequency and cell should be used for the same frequency.
6. For Initial adjustment two knobs are provided on high frequency generator, one is marked
with „Adj‟ the position of the needle on the Ammeter is adjusted and the knob marked „Gain‟
is used to increases the sensitivity of the instrument for greater deflection if desired.
7. The ammeter is used to notice the number of maximum deflections while micrometer is
moved up and down in liquid.
76
77
RESULT: .
Velocity of ultrasonic wave in the given liquid and solid =..............m/s
Compressibility of the given liquid and solid = .............. m2/N
78
Diagram
79
BANDGAP DETERMINATION OF A SEMICONDUCTOR
Expt No :
Date :
AIM:
To determine the width of the forbidden energy in a semiconductor diode
APPARATUS REQUIRED:
Point Contact Diode, Heating Arrangement To Heat The Diode, Ammeter, Voltmeter, Thermometer
FORMULAS USED:
Band gap emergy Eg (eV )= 0.198 x Slope
or
Band gap energy Eg = intercept/slope where Slope = dy/dx
Ig – Saturation current in µA
T – Absolute temperature in Kelvin
Expansion of the symbols:
Symbol
Explanation
Unit
Ig
Saturation current
µA
T
Absolute temperature
Kelvin
PROCEDURE:
The circuit is given as shown in fig. The point contact diode and the thermometer is immersed in a
water (or) oil bath, in such a way that the thermometer is kept nearby the diode. The power supply is
kept constant (say 4 volts). The heating mantle is switched ON and the oil bath is heated up to 70C.
Now the heating mantle is switched OFF and the oil bath is allowed to cool
slowly. For every one degree fall of temperature the micro ammeter reading(Is) is noted.A graph is
plotted taking 1000/T along X axis and log Is along negative Y axis.(Since Is is in the order of micro
amperes, log Is value will come in negative). A straight line is obtained as shown in model graph .
80
TABULAR COLUMN:
Measurement of current for various temperatures
Power supply = ……….V
Room temperature = ……….. C
Current = …………..µA
S.No
Temp in K
°C
Voltage V
103/T K-1
Current Is x
Log Is A
µA
CALCULATIONS:
81
By finding the slope of the straight line, the band gap energy can be calculated using the given
formula. The same procedure can be repeated for various constant power supplies.
RESULT: .
The band gap energy of the given diode is : ……………….eV
82