A short soleniod of radius a, number of turns per unit length `n_(1)`, and length L is kept coaxially inside a very long solenoid of radius b, number of turns per unit length `n_(2)`. What is the mutual inductance of the system?

Options

A. `mu_(0)pib^(2)n_(1)n_(2)L`
B. `mu_(0)pia^(2)n_(1)n_(2)L^(2)`
C. `mu_(0)pia^(2)n_(1)n_(2)L`
D. `mu_(0)pib^(2)n_(1)n_(2)L^(2)`

Answer

C

Explanation

`M=mu_(0)n_(1)n_(2)(L)xx"(Area of small coil)"`
= `mu_(0)n_(1)n_(2)(L)(pia^(2))`.