A magnetic field, confined in a cylindrical region of radius R, is changing at the rate of 4T/s.  A conducting rod PQ of length $\sqrt{\frac{3}{2}}R$ is placed in the region as shown. The induced emf across the rod $i\frac{R^2}{6}(\pi +n)V$ Later, the two ends of the rod are joined by straight conducting wires to the center C , so that the circuit is completed. The resistance of this entire loop is ‘r’. At time ‘t’, the magnetic field in the cylindrical region is B. At time t, magnetic force acting on the rod is given by $\frac{B{R}^3}{ar}(\pi +b)V\sqrt{2}$