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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