A conductor wire ABCDE, with each arm 10 cm long, is placed in a magnetic field B = 1/√2 T perpendicular to its plane, as shown in the original figure. The conductor is pulled to the right with constant speed 10 cm/s. The induced emf between points A and E i s ______ mV.
Physics · Electromagnetic Induction · motional emf and induced emf in rotating rod
JEE Mains 2025 4 April Morning Shift

Question

A conductor wire ABCDE, with each arm 10 cm long, is placed in a magnetic field B = 1/√2 T perpendicular to its plane, as shown in the original figure. The conductor is pulled to the right with constant speed 10 cm/s. The induced emf between points A and E i s ______ mV.

Physics · Electromagnetic Induction · motional emf and induced emf in rotating rod

JEE Mains 2025 4 April Morning Shift

G1 Physics · Accepted Answer

For a rigid conductor translating with uniform velocity v in a uniform magnetic field B, the motional emf between two points is ε = ∫(v×B)·dℓ = (v×B)·(rE-rA). From the geometry in the source figure, the effective displacement between A and E along the direction of v×B is 10√2 cm = 0.10√2 m. Given, v = 10 cm/s = 0.10 m/s, B = 1/√2 T. Therefore, ε = vB(0.10√2) = (0.10)(1/√2)(0.10√2) = 0.010 V = 10 mV. Answer: 10.