A conducting rod AC of length 4ℓ rotates about point O in a uniform magnetic field into the page. AO=ℓ and OC=3ℓ. Select the correct relations.

Question

G1 Physics · Accepted Answer

For a rotating rod, the potential difference between two points at radii r₁ and r₂ is ΔV=½Bω(r₂²-r₁²). Hence Vₒ-V꜀=½Bω(3ℓ)²=9Bωℓ²/2, and Vₐ-V꜀=½Bω[(3ℓ)²-ℓ²]=4Bωℓ². Therefore B and C are correct.