Question

Figure below shows two infinitely long and thin current carrying conductors $X$ and $Y$ kept in vacuum, parallel to each other, at a distance ${}^{\prime }a$
Define ampere, in terms of force between two current carrying conductors

Answer 1

Definition of $1ampere$ :-

$1ampere$ is the current when flowing in each of two infinitely long parallel conductors $1metre$ apart in vacuum produces between them a force of exactly $2\times {10}^{-7}$ newton per metre of length.