Q. 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
A) $1\ N/m$
B) $2 \times 10^{- 7}N/m$
C) $1 \times 10^{- 2}N/m$
D) $4\pi \times 10^{- 7}N/m$
Explanation
(b) Force per unit length on two parallel current carrying conductors is given by $\frac{F}{l} = 10^{- 7} \times 2\frac{i_{1}i_{2}}{a}$
$\Rightarrow \frac{F}{l} = 10^{- 7} \times 2 \times \frac{1 \times 1}{1} = 2 \times 10^{- 7}N/m$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.