In a coil of resistance 100 Ω, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is:

$250\,Wb$

$ \text{Induced Current } = \frac{\xi}{R} = \frac{1}{R} \frac{d\phi}{dt}$

$ \Delta \phi= IR\Delta t = R \times \text{Area under graph} = 100 \times 2.5 Wb= 250 Wb$