A cell of emf 2.2 V gives a current of 0.2 A through a resistance of \( 9\,\Omega \). The internal resistance of the cell will be
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 2\,\Omega \)
The emf drives the current through the external resistance \( R \) and the internal resistance \( r \) in series, so the total resistance is \( R + r \).
\( \displaystyle E = I(R + r) \;\Rightarrow\; r = \frac{E}{I} - R \)
\( \displaystyle r = \frac{2.2\,\mathrm{V}}{0.2\,\mathrm{A}} - 9\,\Omega = 11\,\Omega - 9\,\Omega = 2\,\Omega \)