Question

The figure below is a graph of the magnitude B versus time for a magnetic field that passes through a fixed loop and is oriented perpendicular to the plane of the loop. Rank the magnitudes of the emf generated in the loop at the three instants indicated from largest to smallest.

Answer 1

a>b>c
c>a>b
b>c>a
b>a>c
a>c>b
c>b>a

Answer 2

Faraday's law is that the emf around is equal to the negative rate of change of the flux of B field through the loop.
\[emf = - \frac{ d \Phi_B }{ dt }\]
The flux of B is the integral of the B field inside the loop that is perpendicular to the plane of the loop\[\Phi_B\]
So this quantity, the B flux, is large when the B field perpendicular to the loop is large. You can assume for this problem that the B field is the same everywhere in the loop.

The magnitude of the emf is larger when the B flux is changing faster.