(i) When the magnet is rotated about its own axis, then due to symmetry of magnet the magnetic flux linked with circular coil remains unchanged, hence no emf is induced at terminals of coil.
(ii) When the magnet is rotated about an axis perpendicular to the length, the positions of N and S poles of magnet changes continuously; so the magnetic flux linked with the coil changes continuously; hence the emf is induced at the terminals of the coil.