Twо cоplаnаr аnd cоncentric circular loops of wire with radii r 1 = 12 . 00 c m and r 2 = 9 . 00 c m carry currents of I 1 = 5 . 00 A and I 2 = 3 . 00 A in directions shown in Fig. 3.1. (a) What are the magnitude and direction of the magnetic field at the center of the two loops? (b) If r 1 remains fixed at 12 . 00 c m and r 2 is a variable, determine the value of r 2 such that the net electric field at the center of the loops is zero. If the loops are placed around a solenoid that has a circular cross section of radius r = 10 . 00 c m with loop 2 ( r 2 = 9 . 00 c m ) inside the solenoid and loop 1 ( r 1 = 12 . 00 c m ) surrounding the solenoid shown in the end view of Fig. 3.2. The solenoid is 2 . 00 m long and wound with 50 turns of wire. (c) If the current in the solenoid is 1 . 00 A , what are the magnitude and direction of the magnetic field at the center of the two loops? (d) If the current in the solenoid is reduced to zero in 3 . 00 s , what is the magnitude of the average induced electromotive force (emf) in loop 1 and (e) what is the magnitude of the average induced electromotive force in loop2? fig_q19_final.jpg