A battery of $e m f 8 \mathrm{~V}$ and internal resistance $0.5 \Omega$ is being charged by a 120 V dc supply using a series resistor of $15.5 \Omega$. The terminal voltage of 8 V battery during charging is

• Correct answer
  A

  11.5 V
• B

  1.15 V
• C

  115 V
• D

  0.5 V

Solution

$I=\frac{120-8}{15.5+0.5}=7 \mathrm{~A}$ $\therefore \quad$ The potential difference across 8 V battery is $\mathrm{V}=\mathrm{E}+\mathrm{I}_{\mathrm{r}}=8+7 \times 0.5=11.5 \mathrm{~V}$

Hence, the correct answer is option: 'A'.