The figure shows three circuits I, II and III which are connected to… | JEE Main 2017 (9 Apr, Shift 1)

Q46JEE Main 2017 · 9 APR · SHIFT 1Medium

Electrical Power & Heating Effect

The figure shows three circuits I, II and III which are connected to a 3V battery. If the powers dissipated by the configurations I, II and III are P1, P2 and P3 respectively, then:

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Answer: (c)

Same 3 V across each, so $P = V^2/R$ : smaller $R$ means more power.
I: the five $1\ \Omega$ resistors form a balanced Wheatstone bridge, $R_1 = 1\ \Omega$ .
II: the two $2\ \Omega$ sides and the $1\ \Omega$ middle are in parallel, $R_2 = 0.5\ \Omega$ .
III: $(2 \parallel 2) + 1 = 2\ \Omega$ .
$R_2 < R_1 < R_3$ , so the answer is (c) $P_2 > P_1 > P_3$ .

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