The value of X for which the galvanometer in the figure shows a null deflection is:
4Ω.
8Ω.
4.5 Ω.
1Ω.
An ammeter of full scale deflection 5.00 mA is being used to read a current of size 5.00 A.
This can be achieved by:
Connecting it series with a resistance of 980.00 Ω.
Connecting it in parallel with a resistance of 0.49 Ω.
Connecting it in parallel with a resistance of 0.02 Ω.
Connecting it in parallel with a resistance of 49.95 Ω.
The set up in the figure is used to study the relationship between current (I) and potential difference (V) for a wire X.
The rheostat Y is used to:
Keep the temperature constant.
Vary the resistance of the wire.
Vary the current in the circuit.
Vary electromotive force.
If the material X is a copper wire, the relationship between V and I when the switch is closed at constant temperature is:
Lenz’s law.
Ohm’s law.
Hooke’s law.
Coulomb’s law.
The ammeter is connected as shown because it has:
A very high resistance and so allows little current to flow through it.
Very low resistance and so alters the current flowing through it.
Very high resistance and so allows high current to flow through it.
Very low resistance and so does not alter the current flowing through it.
