Aim:- Aim of the experiment to study V-I characteristics of an index scan lamp.
Apparatus Required:-
S.
No. |
Name
of Equipment |
Type |
Range |
Quantity |
1. |
Incandescant lamp |
- |
200 W |
1 |
2. |
Voltmeter |
PMMC |
|
1 |
3. |
Ammeter |
PMMC |
|
1 |
4. |
Rheostat |
Tube Type |
128ohm, 2.5Amp |
1 |
Theory:- There is a practical no
change in the resistance value in case of some alloys used in electrical works
like manganin for a considerable variation of temperature in general for alloys
the increase in resistance is very slight with increase in temperature for all
pure metal like copper aluminum etc the resistance increase with an increase in
temperature the resistance of such conducting materials at working temperature
of tea degree Celsius can be found out by using equations given below
Resistance
at t0C,Rt=R0(1+αt)
Where
R0=Resistance at 00C
α = temperature
coefficient of the conducting material
however
the resistance of carbon and electros decreases with increase in temperature to
these are also the conducting materials their temperature coefficient Alpha is
said to be negative the resistance of all insulating material sharping decrease
with increase in temperature.
Circuit diagram:- the aim of experiment is
to study the variation of resistance with rise in temperature the resistance of
the filament of in descant lamp tungsten increase with rise in temperature as
such a bulb has been chosen for this experiment the temperature of the filament
depends upon the heat which it turns depends upon we square by R where we is
the voltage applied across the filament of the bulb and R is your assistance
does by applying different voltage to the filament of the bulb different amount
of heat can be produced and different temperature can be obtained.
Procedure:-
1. Connect the circuit as
shown in the diagram with the switch bracket as slash W is in off position.
2. Switch on DC supply close
this which and very the rheostat to obtain different voltage and current
values. note the voltage and corresponding current values. Record the calculate
percentage error.
3. Switch off supply then open
the switch.
Observation Table:-
Sr. No. |
Vin(Volts) |
Iin(Amp) |
R=v/I |
1 |
20 |
0.22 |
90.90 |
2 |
40 |
0.28 |
142.86 |
3 |
60 |
0.34 |
176.47 |
4 |
80 |
0.40 |
200.00 |
5 |
100 |
0.46 |
217.39 |
6 |
120 |
0.50 |
240.00 |
7 |
140 |
0.34 |
259.26 |
Least count of Voltmeter = 4V
Least count of Ammeter = 0.02 amp
Remark:-The characteristic is non
linear.
Precautions:-
1. Make the connections
properly.
2. Note the reading of
voltmeter and ammeter properly.
3. Remove insulation from the
connecting wire so that the current will flow properly.
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