A light brass wire of total resistance R=1ohm is wound around a disc of plastic (den =1 gm/cc) &suspended so as 2 make an essentially undamped torsion pendulum of period T = 10 sec.......The disc is initially at rest in a uniform magnetic field , B=10,000Gauss , with B in d plane of d loop,i.e. theta = 90.......At time t=0,switch S is switched to M and then at t1=10^(-4)sec switched to N....Find d amplitude of d ensuing oscillations as a function of t..............