The source figure shows two cases (a) and (b) with an electric-field vector and the direction of an induced magnetic-field line. In each case, decide whether the magnitude of E is increasing or decreasing.

Question

G1 Physics · Accepted Answer

Use the Ampere-Maxwell right-hand rule: the circulation direction of B gives the direction of displacement current and hence the sign of dE/dt. In both sketches dE/dt is opposite to E, so the electric-field magnitude is decreasing in both cases. Option C.