If an iron rod is placed inside a coil, what happens to the induced current?

$A$ short-circuited coil is placed in a time-varying magnetic field. Electrical power is dissipated due to the current induced in the coil. If the number of turns were to be quadrupled and the wire radius halved,the electrical power dissipated would be

$A$ dynamo is a device for converting:

The plane of a circular coil of resistance $7.5 \ \Omega$ is placed perpendicular to a uniform magnetic field. The flux $\phi$ (in weber) through the coil varies with time $t$ (in second) as $\phi = 2t^2 + 3t - 2$. The induced power in the coil at time $t = 3 \ s$ is (in $W$)

As shown in the figure,$P$ and $Q$ are two coaxial conducting loops separated by some distance. When the switch $S$ is closed,a clockwise current $I_P$ flows in $P$ (as seen by $E$) and an induced current $I_{Q_1}$ flows in $Q$. The switch remains closed for a long time. When $S$ is opened,a current $I_{Q_2}$ flows in $Q$. Then the directions of $I_{Q_1}$ and $I_{Q_2}$ (as seen by $E$) are:

$A$ flexible wire bent in the form of a circle is placed in a uniform magnetic field perpendicular to the plane of the coil. The radius of the coil changes as shown in the figure. The graph of induced $emf$ in the coil is represented by