Two identical cells, each of emf 9.0 V and internal resistance 1.0 Ω, are connected in a parallel arrangement. The maximum current that can be drawn from this combination of cells is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 18.0 A
Identical cells in parallel keep the same emf, while their internal resistances combine in parallel. The current is maximum when the external resistance is zero (the terminals are shorted), so only the internal resistance limits it.
\( \displaystyle E_{\mathrm{eq}} = 9.0\,\mathrm{V} \)
\( \displaystyle r_{\mathrm{eq}} = \frac{1.0\,\Omega \times 1.0\,\Omega}{1.0\,\Omega + 1.0\,\Omega} = 0.5\,\Omega \)
\( \displaystyle I_{\max} = \frac{E_{\mathrm{eq}}}{r_{\mathrm{eq}}} = \frac{9.0\,\mathrm{V}}{0.5\,\Omega} \)
\( \displaystyle I_{\max} = 18.0\,\mathrm{A} \)