In the figure,the switch $S$ is closed so that a current flows in the iron-core inductor which has inductance $L$ and the resistance $R$. When the switch is opened,a spark is obtained at the contacts. The spark is due to

The circuit shown in the figure contains an inductor $L = 25 \text{ mH}$, a capacitor $C_0 = 10 \text{ } \mu\text{F}$, a resistor $R_0 = 5 \text{ } \Omega$ and an ideal battery of $20 \text{ V}$. The circuit also contains two keys $K_1$ and $K_2$. Initially, both the keys are open and there is no charge on the capacitor. At an instant, key $K_1$ is closed and immediately after this, the current in $R_0$ is found to be $I_1$. After a long time, the current attains a steady state value $I_2$. Thereafter, $K_2$ is closed and simultaneously $K_1$ is opened, and the voltage across $C_0$ oscillates with amplitude $V_0$ and angular frequency $\omega_0$. Match the quantities mentioned in $List-I$ with their values in $List-II$ and choose the correct option.

$List-I$	$List-II$
$(P)$ The value of $I_1$ in Ampere is	$(1)$ $0$
$(Q)$ The value of $I_2$ in Ampere is	$(2)$ $2$
$(R)$ The value of $\omega_0$ in kilo-radians/s is	$(3)$ $4$
$(S)$ The value of $V_0$ in Volt is	$(4)$ $20$
	$(5)$ $200$

Two long parallel wires whose centres are at a distance $d$ apart carry equal currents in opposite directions. If the flux within the wires is neglected,the inductance of such an arrangement of wire of length $l$ and radius $a$ will be

$A$ circular coil and a bar magnet placed nearby are made to move in the same direction. The coil covers a distance of $1\, m$ in $0.5\, s$ and the magnet covers a distance of $2\, m$ in $1\, s$. The induced emf produced in the coil is.....$V$.

$A$ coil is placed in a magnetic field of $1 \, T$. Its area changes at a rate of $\frac{5 \, m^2}{ms}$. If the current in the coil changes from $1 \, A$ to $2 \, A$ in $2 \times 10^{-3} \, s$,what is the inductance of the coil in $H$?

The variation of induced emf $(E)$ with time $(t)$ in a coil if a short bar magnet is moved along its axis with a constant velocity is best represented as