The current in a long solenoid of radius R and having n turns per unit length is given i=i0sinωt. A coil having N turns is wound around it near the centre. Find (a) the induced emf in the coil and (b) the mutual inductance between the solenoid and the coil.
A solenoid coil has 10 turns per cm along its length and a cross sectional area of 10 cm2. 100 turns of another wire are wound round the first solenoid coaxially. The two coils are electrically insulated from each other. The mutual inductance between the two coils is