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Problem 2 - Olympiad

A metallic rod of length 1 m slides with velocity 5 m/s on two parallel rails separated by 1 m in a magnetic field B = 2 T perpendicular to the plane. If the rod has resistance 4 Ω and rails are resistanceless, what is the power delivered by the external agent maintaining constant velocity?

Correct: B

Induced EMF = Blv = 2*1*5 = 10 V. Current = 10/4 = 2.5 A. Power = I²R = (2.5)²*4 = 25 W. Alternatively, P = F*v = (Bil)*v = (2*2.5*1)*5 = 25 W.