A long solenoid consisting of `1.5xx10^3 turns//m` has an area of cross-section of `25 cm^2`. A coil C, consisting of 150 turns `(N_c)` is wound tightly around the centre of the solenoid. Calculate for a current of 3.0 A in the solenoid (a) the magnetic flux density at the centre of the solenoid, (b) the flux linkage in the coil C, (c) the average emf induced in coil C if the current in the solenoid is reversed in direction in a time of 0.5 s.`(mu0=4pixx10^-7 T.m//A)`.