Magnetic flux (in weber) in a closed circuit of resistance $20\,\Omega$ varies with time $t(s)$ as $\phi = 8t^2 - 9t + 5$. The magnitude of the induced current at $t = 0.25\,s$ will be $...mA$.

When a bar magnet is pushed towards the coil,along its axis,as shown in the figure,the galvanometer pointer deflects towards $X$. When this magnet is pulled away from the coil,the galvanometer pointer:

$A$ vertical bar magnet is dropped from the shown position on the axis of a fixed metallic coil as shown in Fig-$I$. In Fig-$II$,the magnet is fixed and a horizontal coil is dropped. If the acceleration of the magnet and coil are $a_1$ and $a_2$ respectively,then:

$A$ coil of effective area $3 \,m^2$ is placed at right angles to a magnetic field of induction $0.05 \,Wb/m^2$. If the field is decreased to $20 \%$ of its original value in $10 \,s$, the e.m.f. induced in the coil will be: (in $\,mV$)

Two conducting wire loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop is

$A$ circular loop of flexible conducting material is kept in a magnetic field directed perpendicularly into its plane. By holding the loop at diametrically opposite points,it is suddenly stretched outwards,then