Two resistances, 6 Ω and 3 Ω, are connected in parallel to an electrical cell of emf 6 V and 1 Ω internal resistance. The reading of the voltmeter connected to the circuit will be |
4 V 2.4 V 3 V 6 V |
4 V |
The correct answer is Option (1) → 4 V Given: Resistances: $R_1 = 6\ \Omega$, $R_2 = 3\ \Omega$ Cell emf: $E = 6\ \text{V}$ Internal resistance: $r = 1\ \Omega$ Equivalent resistance of parallel combination: $\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2} = \frac{1}{6} + \frac{1}{3} = \frac{1 + 2}{6} = \frac{3}{6} = \frac{1}{2}$ $R_{\text{eq}} = 2\ \Omega$ Total resistance in circuit: $R_{\text{total}} = R_{\text{eq}} + r = 2 + 1 = 3\ \Omega$ Total current from the cell: $I = \frac{E}{R_{\text{total}}} = \frac{6}{3} = 2\ \text{A}$ Voltage across the parallel combination (also the voltmeter reading): $V = I \cdot R_{\text{eq}} = 2 \cdot 2 = 4\ \text{V}$ Voltmeter reading = 4 V |