A storage battery of emf 8.0 V and internal resistance 0.5 Ω is being charged by a 60 V dc supply using a series resistor of 12.5 Ω. The terminal potential difference between the terminals of the battery during charging is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 10.0 V
Given:
Battery emf: $E = 8 \, \text{V}$
Internal resistance: $r = 0.5 \, \Omega$
Series resistor: $R = 12.5 \, \Omega$
Supply voltage: $V_s = 60 \, \text{V}$
Current through circuit during charging:
$I = \frac{V_s - E}{R + r} = \frac{60 - 8}{12.5 + 0.5} = \frac{52}{13} = 4 \, \text{A}$
Terminal voltage of battery:
$V = E + I r = 8 + 4 \cdot 0.5 = 8 + 2 = 10 \, \text{V}$
Answer: Terminal potential difference $V = 10 \, \text{V}$