The magnetic field B, crossing normally a square metallic plate of area 4 m$$^2$$, is changing with time as shown in the figure. The magnitude of the induced emf in the plate during $$t = 2$$ s to $$t = 4$$ s, is _______ mV.

$$|\epsilon| = \left| \frac{d\Phi}{dt} \right|$$

$$\Phi = B \times A$$

$$|\epsilon| = A \times \left| \frac{dB}{dt} \right|$$

$$\frac{dB}{dt} = \frac{B_2 - B_1}{t_2 - t_1} = \frac{8\text{ mT} - 4\text{ mT}}{4\text{ s} - 2\text{ s}}$$

$$\frac{dB}{dt} = \frac{4\text{ mT}}{2\text{ s}} = 2\text{ mT/s}$$

$$|\epsilon| = 4\text{ m}^2 \times 2\text{ mT/s}$$

$$|\epsilon| = 8\text{ mV}$$