A battery of internal resistance r, when connected across \(2~\Omega\) resistor supplies a current of 4 A. When the battery is connected across a \(5~\Omega\) resistor, it supplies a current of 2 A. The value of r is:
1. | \(2~\Omega\) | 2 | \(1~\Omega\) |
3. | \(0.5~\Omega\) | 4. | Zero |
A battery is charged at a potential of 15 V for 8 hours when the current flowing is 10 A. The battery on discharge supplies a current of 5 A for 15 hours. The mean terminal voltage during discharges is 14 V. The "Watt hour" efficiency of the battery is:
1. 80%
2. 90%
3. 87.5%
4. 82.5%
A battery of e.m.f. E and internal resistance r is connected to a variable resistor R as shown below. Which one of the following is true?
1. | Potential difference across the terminals of the battery is maximum when R = r. |
2. | Power delivered to the resistor is maximum when R = r. |
3. | Current in the circuit is maximum when R = r. |
4. | Current in the circuit is maximum when R >> r. |