Question

SI unit of electric current "ampere" is the current, which when flows through each of two parallel wires spaced 1m apart in vacuum and of infinite length will give rise to a force between then equal to​

Answer 1

F=4pia×10‐⁷/2pia=2×10‐⁷N/M

Answer 2

Given : A current when flows through each of two parallel wires spaced 1m apart in vacuum and of infinite length

We know that

$\mathrm{F}=\left(\mu_{0} / 2 \pi\right)\left[\left(l_{1} I_{2} \ell\right) / \mathrm{y}\right]$

$(F / \ell)=\left[\left(4 \pi \times 10^{-7}\right) / 2 \pi\right] \times[(1 \times 1) / 1]$

$=2 \times 10^{-7} \mathrm{~N} / \mathrm{m}$

So the force between them is  equal to $=2 \times 10^{-7} \mathrm{~N} / \mathrm{m}$.