Two co-axial solenoids are made by a pipe of cross sectional area `10 cm^2` and length 20 cm If one of the solenoid has 300 turns and the other 400 turns, their mutual inductance is........
Options:
(a) `4.8xx 10^(-4) H`
(b) `4.8xx 10^(-5) H`
(c) `2.4 xx10^(-4) H`
(d) `4.8 xx10^4 H`