A planar loop of wire rotates in a uniform magnetic field....

$Φ = \overset{\to}{B} \cdot \overset{\to}{A} = BAcos\theta = BAcos\left(\omegat\right)$

$e = \left|\dfrac{dϕ}{dt}\right| = BA\omega sin\left(\omegat\right)$

When $\omegat = \dfrac{\pi}{2}$
$∵ ϕ$ will be minimum.
$∴ e$ will be maximum
$t = \dfrac{\dfrac{\pi}{2}}{\dfrac{\pi}{5}} = 2 . 5s$

When $\omegat = \pi$
$∵ ϕ$ will be maximum.
$∴ e$ will be minimum
$t = \dfrac{\pi}{\pi / 5} = 5s$