Two resistances, 6 \( \Omega \) and 3 \( \Omega \), are connected in parallel to an electrical cell of emf 6 V and 1 \( \Omega \) internal resistance. The reading of the voltmeter connected to the circuit will be
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 4\,\mathrm{V} \)
An ideal voltmeter connected across the cell reads its terminal voltage, \( V = \varepsilon - I r \), which is the voltage across the external resistance.
\( \displaystyle R_{\mathrm{ext}} = \frac{6 \times 3}{6 + 3} = 2\,\Omega \)
\( \displaystyle I = \frac{\varepsilon}{R_{\mathrm{ext}} + r} = \frac{6}{2 + 1} = 2\,\mathrm{A} \)
\( \displaystyle V = \varepsilon - I r = 6 - 2 \times 1 = 4\,\mathrm{V} \)