• # question_answer A varying magnetic flux linking a coil is given by $\theta =3{{t}^{2}}$. The magnitude of induced emf in the loop at $t=3s,$ is: A)  $3\,V$                       B)  $9\,V$C)  $18\,V$                     D)  $27\,V$

As, $|\varepsilon |=\left| \frac{d\phi }{dt} \right||\,\,=\frac{d}{dt}\,(3{{t}^{2}})=6t=18V$ (at $t=3s$)