# Homework Help: Mutual Inductance

1. Oct 20, 2009

### songoku

1. The problem statement, all variables and given/known data
A mutual inductor consists of two coils X and Y arranged so that one quarter of the magnetic flux produced by X links with Y. When X is used as the primary coil and Y as the secondary, the mutual inductance is M. What is the mutual inductance when Y is used as primary coil and X as the secondary?

a. M/4
b. M/2
c. M
d. 2M
e. 4M

2. Relevant equations
$$E=-M\frac{\Delta I}{\Delta t}$$

3. The attempt at a solution
I think the answer is (c) because M is independent whether X or Y is the primary one. Am I right?

Thanks

2. Oct 20, 2009

### rl.bhat

Yes. M12 = M21