The e.m.f. induced in a secondary coil is `20000 V` when the current breaks in the primary coil. The mutual inductance is `5H` and the current reaches to zero in `10^(-4) sec` in the primary. The maximu current in the primary before it breaks is

Options

A. 0.1 A
B. 0.4 A
C. 0.6 A
D. 0.8 A

Answer

B

Explanation

`e=-M . ((i_2-i_1))/("time"), 2xx 10^4=(-5(0-i_1))/(1-^(-4))`
`Mi=(4mu_0xxl^2i)/(piLsqrt2)`