Physics - EMI/AC Question with Solution | TestHub

The diagram shows a circuit having a coil of resistance $R$ and inductance $L$ connected to a conducting rod PQ which can slide on a perfectly conducting circular ring of radius 10 cm with its centre at ' P '. Assume that friction \& gravity are absent and a constant uniform magnetic field of 5 T exists as shown in figure. At $\mathrm{t}=0$, the circuit is switched on and simultaneously a time varying external torque is applied on the rod so that it rotates about P with a constant angular velocity $40\mathrm{rad}/\mathrm{s}$. Find magnitude of this torque when current reaches half of its maximum value. Neglect the self inductance of the loop formed by the circuit. Resistance $\mathrm{R}=1\Omega$. If your answer is $\mathrm{x}\times 10^{-4}\mathrm{Nm}$ fill value of $\mathrm{x}/25$