Two coaxial solenoids are made by winding thin insulated wire over a pipe of cross-section area `A = 10cm^2` and length l = 20 cm. If one of the solenoids has 300 turns and the other 400 turns, their mutual inductance is ....... `[mu_0=4pixx10^(-7) "TmA"^(-1)]`

Options

A. `2.4pixx10^(-4)` H
B. `2.4pixx10^(-5)` H
C. `4.8pixx10^(-4)` H
D. `4.8pixx10^(-5)`H

Answer

A

Explanation

Mutual inductance ,
`M=(mu_0 N_1N_2A)/l`
`=(4pixx10^(-7)xx300xx400xx10xx10^(-4))/0.2`
`=24000000 pi xx 10^(-11)`
`therefore M=2.4 pixx10^(-4)` H