Question

The magnetic flux, through a coil, present in a magnetic field, directed perpendicular to its plane, varies with time (in second) according to the relation.

ϕ_B = 6t² + 7t + 1 (ϕB in miliweber)

Find the magnitude of the induced emf in the coil at t = 2s. Also find the current, and its direction, in the resistance R, if R = 10Ω

Answer 1

The direction of current, in the resistance R, will be as shown, according to lenz’s rule, i.e., from left to right. (As the magnetic flux is increasing with time, induced current has to oppose its cause. For this, it has to set up its own magnetic field, in a direction opposite to the applied field. This would require the induced current to flow in an anticlockwise sense in the coil).