The back e.m.f. induced in a coil, when current change from `1` ampere to zero in one millisecond , is `4` volt, the self-inductance of the coil is

Options

A. `1 H`
B. `4 H`
C. `10^(-3)H`
D. `4xx10^(-3)H`

Answer

D

Explanation

`e=-L(di)/(dt)`but `e=4V` and (di)/(dt)=(0-1)/(10^(-3))=-1//10^(-3)`
`:. (-1)/(10^(-3)(-L)=4=L=4xx10^(-3)` henry