A battery (internal resistance negligible) is connected to two resistors

PHYSICS · Single correct · A Level · Physics · Electricity · Electricity

Problem

A 12 V12\,\text{V} battery (internal resistance negligible) is connected to two resistors, R1=10 ΩR_1 = 10\,\Omega and R2=20 ΩR_2 = 20\,\Omega, but the exact arrangement is unknown. An ideal ammeter measures the total current supplied by the battery, and an ideal voltmeter is connected across R2R_2 only. The meters show I=0.40 AI = 0.40\,\text{A} and V=8.0 VV = 8.0\,\text{V}. Which arrangement is consistent with these readings? (a) R1R_1 and R2R_2 are connected in parallel, and the voltmeter is correctly across R2R_2. (b) R1R_1 and R2R_2 are connected in series, but the voltmeter is actually across R1R_1. (c) R1R_1 and R2R_2 are connected in series, and the voltmeter is correctly across R2R_2. (d) R1R_1 and R2R_2 are connected in parallel, and the ammeter is mistakenly inserted only in the branch containing R2R_2.

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