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. `2xx10^(-7)N//m`
C. `1xx10^(-2)N//m`
D. `4pixx10^(-7)N//m`

Answer

B

Explanation

Force per unit length on two parallel current carrying conductor is given by `(F)/(1)=10^(-7)xx2(i_(1)i_(2))/(a)`
` implies (F)/(1)=10^(-7)xx2xx(1xx1)/(1)=2xx10^(-7)N//m`