In a uniform and constant magnetic field of induction $B$, two long conducting wires $ab$ and $cd$ are kept parallel to each other at distance $l$ with their plane perpendicular to $B$. The ends $a$ and $c$ are connected together by an ideal inductor of inductance $L$. A conducting slider wire $PQ$ is imparted a speed $v_0$, at time $t=0$. The situation is shown in the figure. AT time $t=\frac{\pi \sqrt{mL}}{4Bl}$, the value of current $I$ through the wire $PQ$ is (ignore any resistance, electrical as well as mechanical)

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The current following through an inductance coil of self inductance $6 \mathrm{mH}$ at different time instants is as shown. The emf induced between $t=20 \mathrm{s}$ and $t=40 \mathrm{s}$ is nearly

In a circuit current decrease from $5A$ to $0A$ is $0·1s$. If the average induced e.m.f is $200v$, calculate the self inductance of the circuit and write is unit.

Current in a coil with self-inductance $2 \mathrm{H}$ is increasing according to$I=\left(2{\mathrm{sint}}^2\right)$ ampere. Amount of energy spent during the period when current changes from $0$ to $2 \mathrm{A}$ is $\underline{ }$