The unit of electric current "ampere" is the current which when flowing through each of two parallel wires spaced `1 m` apart in vacuum and of infinite length will give rise to a force between them equal to

Options

A. 1 N/m
B. `2 xx 10^(-7) N//m`
C. `1 xx 10^(-2) N//m`
D. `4pi xx 10^(-7) N //m`

Answer

B

Explanation

`(F)/(I) = (mu_(0) I_(1) I_(2))/(2pi r) = (4pi xx 10^(-7) xx 1^(2))/(2pi xx 1) = 2 xx 10^(-7)` N/m.