Question

using the concept of force b/w two infinetly long parallel current carrying conductor define 1 apmere of current

Answer 1

1 ampere is defined as that (constant direct electric) current, which, if maintained in each of two infinitely long straight parallel wires of negligible cross-section placed 1 metre apart in a vacuum, will produce between the wires a force of

$2 \times {10}^{ - 7}$

newtons per metre length...