Physics · May / June 2025 · Paper 12 · Question 32

A square coil is placed in a horizontal uniform magnetic field. The plane of the coil is perpendicular to the magnetic field. The coil is now rotated about an axis through P at a steady rate. The coil rotates through 180°. Which diagram shows how the electromotive force (e.m.f.) induced in the coil varies as it rotates through 180°?

1. Agraph: e.m.f. rises from 0 at 0° to a maximum then falls back to 0 at 180°
2. Bgraph: e.m.f. starts at a maximum at 0° and decreases, crossing zero, becoming negative at 180°
3. Cgraph: e.m.f. sinusoidal, starting at 0, rising to a maximum, crossing zero, reaching a negative minimum, returning to 0 at 180°
4. Dgraph: e.m.f. decreases linearly from a maximum at 0° to zero at 180°

As printed in the paper