For one coil, kept in 1T external magnetic field, current passing through it increases from 1 A to 2 A in `2 xx 10^(-3)` s. Meanwhile time rate of change of its area is found to be 5 `"m"^2/"ms"` . Then the self inductance of the coil is ____

Options

A. 2 H
B. 5 H
C. 10 H
D. 20 H

Answer

C

Explanation

We have `epsilon=-L (dI)/(dt)`
`therefore - (dPhi)/(dt)=-L (dI)/(dt)`
`therefore d/(dt)(NAB)=L(dI)/(dt)`
`therefore NB(dA)/(dt) =L (dI)/(dt)`
`therefore 1xx1xx5xx1/10^(-3)=L (2-1)/(2xx10^(-3))`
`therefore` L=10 H