Question:

A long solenoid consisting of 1.5×103 turns/m has an area of cross-section of 25 cm2. A coil C, consisting of 150 turns (Nc) is wound tightly around the centre of the solenoid. Calculate for a current of 3.0 A in the solenoid (1)the magnetic flux density at the centre of the solenoid,(2) the flux linkage in the coil C, (3)the average emf induced in coil C if the current in the solenoid is reversed in direction in a time of 0.5 s. (uo = 4π x 10-7 T. m/A)