A wire of length 1 m is moving at a speed of 2 m/s perpendicular homogenous magnetic field of 0.5 T. The ends of the wire are joined to resistance 6 Ω. The rate at which work is being done to keep the wire moving at that speed is (a) 1/3 W (b) 1/6 W (c) 1/12 W (d) 1 W

Answer: (b). e = Blv = 0.5 × 1 × 2 = 1 V At constant speed, mechanical power = electrical power P = e²/R. P = 1²/6 = 1/6 W So the answer is (b) 1/6 W.

A wire of length 1 m is moving at a speed of 2 m/s perpendicular… | MHT CET 2021 (22 Sep, Shift 1)

Q40MHT CET 2021 · 22 SEP · SHIFT 1Medium

Motional EMF

A wire of length 1 m is moving at a speed of 2 m/s perpendicular homogenous magnetic field of 0.5 T. The ends of the wire are joined to resistance 6 $\Omega$ . The rate at which work is being done to keep the wire moving at that speed is

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Answer: (b)

$e = Blv = 0.5 \times 1 \times 2 = 1\text{ V}$
At constant speed, mechanical power = electrical power $P = \dfrac{e^2}{R}$ .
$P = \dfrac{1^2}{6} = \dfrac{1}{6}\text{ W}$
So the answer is (b) $\dfrac{1}{6}$ W.

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