Question

Two coils, A and B, are linked such that emf ℰ is induced in B when the current in A is changing at the rate I. If i current is now made to flow in B, the flux linked with A will be 

(a) (ℰ/I)i 

(b) ℰi I 

(c) (ℰ I)i 

(d) iI/ℰ 

Answer 1

Correct Answer is: (a) (ℰ/I)i 

Let M = mutual inductance between A and B.

e_B = M (di_A/dt)

or ℰ = MI  

or M = ℰ / I

ϕ_A = Mi_B = (ℰ / I) i.