A cell of emf 10 V and the internal resistance \( 1\,\Omega \) is being charged by an external supply of 100 V. An external resistance of \( 8\,\Omega \) is connected to the charging circuit. The current in the circuit is
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 10 A
While a cell is being charged, the supply drives current into its positive terminal, so the emf of the cell opposes the supply. The net emf in the circuit is the difference of the two, and the internal and external resistances are in series.
\( \displaystyle I = \frac{V - E}{R + r} = \frac{100 - 10}{8 + 1} = \frac{90}{9} = 10\,\mathrm{A} \)