The AC voltage across a resistance can be measured using a :
potentiometer
moving coil galvanometer
moving magnet galvanometer
hot wire voltmeter
As we learnt in
To determine the resistance of a galvanometer by half deflection method -
G= galvanometre resistance
R= Extreme resistance
S= Shunt
Procedure
Resistance of galvanometer by half deflection method.
1. Draw the circuit diagram as shown in figure.
2. See that plugs of the resistance boxes are tight.
3. Take out high resistance from the resistance box R and insert the key K1 only.
4. Adjust the value of R so that deflection is maximum, even in number and within scale.
5. Note the deflection. Let it be .
6. Now, insert the key K2 and without changing the value of R adjust the value of S such that deflection in the galvanometer reduces to exactly half the value obtained in step 5 i.e.
7. Note the value of resistance S.
8. Repeat steps 4 to 7 three times taking out different values of R and adjusting S every time.
- wherein
= definite angle
Ig = current passing through galvanometre
K= figuring merit
Moving coil or magnet galvanometer can measure only d.c. values. For A.C. voltage hot wire voltmeter is used.
Option 1)
potentiometer
This option is incorrect
Option 2)
moving coil galvanometer
This option is incorrect
Option 3)
moving magnet galvanometer
This option is incorrect
Option 4)
hot wire voltmeter
This option is correct
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