A solenoid of length 40.0 cm is made of 10,000 circular coils. It carries a steady current of 12.0 A. Near its center is placed a small, flat, circular metallic coil of 200 circular loops, each with a radius of 2.00 mm. This small coil is oriented so that it receives half of the maximum magnetic flux. As witch is opened in the solenoid circuit and its current drops to zero in 25.0 ms.
(a) What was the initial flux through the small coil?
(b) Determine the average induced emf in the small coil during the 25.0 ms.
(c) If you look along the long axis of the solenoid so that the initial 12.0 A current is clockwise, determine the direction of the induced current in the small inner coil during the time the current drops to zero.