A current flows through a rectangular conductor in the presence of uniform magnetic field B pointing out of the page as shown. Then the potential difference VB - VA is equal to (Assume charge carriers in the conductor to be positively charged moving with speed v)

Question

G1 Physics · Accepted Answer

Positive carriers moving with speed v experience qv⃗×B⃗ and separate until qE=qvB, so E=vB. The separation between A and B is c, hence Vᵦ-Vₐ=Ec=Bvc with the sign shown. Hence A.