A conducting wire frame is placed in a magnetic field which is directed into the paper. The magnetic field is increasing at a constant rate. The directions of induced currents in wires AB and CD are

Question

G1 Physics · Accepted Answer

Magnetic flux is Φ=∫B⃗·dA⃗ and induced emf is ε=-dΦ/dt. Apply Lenz’s law for direction and I=ε/R when the circuit is resistive. This gives B to A and D to C.