A uniform magnetic field B⃗ fills a cylindrical region of radius R. A metal rod CD of length ℓ is a chord at perpendicular distance b from the centre. If |dB/dt| is constant, find the magnitude and direction of emf induced in the rod.

Question

G1 Physics · Accepted Answer

For a uniformly changing magnetic field, the induced electric field is tangential. For chord length ℓ, its distance from the centre is b=√(R²-ℓ²/4). Integration along the chord gives |ε|=(ℓ/2)(dB/dt)b. Hence option A.