Question

How can we define an ampere using the concept of the force between two infinitely long parallel current carrying conductors?

Answer 1

One ampere of current can be defined as the amount of current which when flowing (in same direction) through two infinitely long parallel wires separated by one metre produces an attractive force of 2 × 10−7 N/m. The wires must have negligible circular cross-section and they must be placed in vacuum.