$A$ coil having an inductance of $0.5\, H$ carries a current which is uniformly varying from zero to $10\, A$ in $2\, s$. The $e.m.f.$ (in volts) generated in the coil is

$A$ branch of a circuit is shown in the figure. If the current is decreasing at the rate of $10^3 \ A \ s^{-1}$, then the potential difference between $A$ and $B$ is (in $V$)

Current in a circuit falls from $5.0 \, A$ to $0.0 \, A$ in $0.1 \, s$. If an average $emf$ of $200 \, V$ is induced,give an estimate of the self-inductance of the circuit in $H$.

Two coils have self-inductance $L_1$ and $L_2$. The current through them is increasing at a constant rate. If the power dissipated in both the coils is the same, then the ratio of energy stored in the coil having inductance $L_1$ to that in $L_2$ is

$A$ toroid is a long coil of wire ($N$ turns) wound over a circular core. The coefficient of self-induction of the toroid is [The magnetic field in it is uniform and $R >> r$,where $r=$ radius of wire,$R=$ radius of coil] ($\mu_0=$ permeability of free space).

The self-inductance of a coil is $5 \, H$. If a current of $1 \, A$ changes to $2 \, A$ within $5 \, s$ through the coil,the magnitude of the induced $e.m.f.$ will be $... \, V$.