Six Cells each of emf 2 V and internal resistance \( 0.2\,\Omega \) are connected as shown in the figure. The reading of the ideal voltmeter is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → zero
The six identical cells form a closed series loop, so the total emf drives a current through the total internal resistance only. The ideal voltmeter draws no current and does not disturb the loop.
\( \displaystyle I = \frac{6E}{6r} = \frac{6 \times 2\,\mathrm{V}}{6 \times 0.2\,\Omega} = 10\,\mathrm{A} \)
The terminal voltage of each cell is
\( \displaystyle V_{\mathrm{cell}} = E - I r = 2 - 10 \times 0.2 = 0 \)
Across any group of \( n \) cells the voltmeter reads
\( \displaystyle V = n(E - I r) = n \times 0 = 0 \)
So the reading is zero.