(a) Explain mutual induction with the help of two insulated coils (6)

(b) A coil of 800 turns is wound on a wooden former and a current of 5A is passed through it to produce a magnetic flux of 200 micro-webers. A secondary coil of 2000 turns is wound on it. Find the emf induced in the secondary coil when the current is switched off in 0.08sec.