A cylindrical bar magnet is placed along the axis of a circular coil which is rotating about its axis. The coil will have induced in it
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → no induced current
An emf is induced only when the magnetic flux through the coil changes (Faraday's law). The field of a cylindrical bar magnet is symmetric about its axis. When the coil rotates about that same axis, its area, its orientation to the field and its position all stay the same, so the flux through it is constant.
\( \displaystyle \varepsilon = -\frac{d\Phi_B}{dt} = 0 \)
With no emf there is no induced current.