The flux linked with a coil at any instant $'t'$ is given by $\phi = 10{t^2} - 50t + 250$ The induced $emf$ at $t=3s$ is

Question

The flux linked with a coil at any instant $'t'$ is given by
$\phi = 10{t^2} - 50t + 250$
The induced $emf$ at $t=3s$ is

$-190$ $V$