You are given several identical resistances each of value and each capable of carrying a maximum current of one ampere. It is required to make a suitable combination of these resistances of which can carry a current of 4 A. The minimum number of resistances of the type R that will be required for this job is
4
10
8
20
A storage battery is connected to the mains for charging with emf of 12.5 V. The internal resistance of the storage battery is 1 Ω. When the charging current is 0.5 A, the potential difference across the storage battery is
13 V
12.5 V
12 V
11.5 V
A battery is charged at a potential of 15V for 8 h when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 h. The mean terminal voltage during discharge is 14 V. The "watt-hour" efficiency of the battery is
82.5%
80%
90%
87.5%
The current i in the given circuit is
1.6 A
2 A
0.32 A
3.2 A
Potentiometer measures the potential difference more accurately than a voltmeter because
it has a wire of high resistance
it has a wire of low resistance
it does not draw current from external circuit
it draws a heavy current from external circuit
