In which of the following cases emf would be induced-

The correct answer is Option (3) → Whenever the magnetic flux linked with a circuit changes even if the circuit is open.

Electromotive force (emf) is induced whenever the magnetic flux linked with a circuit changes.

☀ When a coil and a magnet move with the same velocity in the same direction ⟶ No emf (relative motion = 0, flux does not change).

☀ When a magnet is rotated about its own axis ⟶ No emf (flux through coil does not change).

☀ Whenever the magnetic flux linked with a circuit changes even if the circuit is open ⟶ Yes, emf induced.

☀ When a closed loop moves totally inside a uniform magnetic field ⟶ No emf (flux does not change).

Correct answer: Only the third case