Quantitatively , the ampere is defined to be the constant current which will produce an attractive force of NUMBER@1 × NUMBER@2 -- NUMBER@3 newton per metre of length between two straight , parallel conductors of infinite length and negligible circular cross section placed one metre apart in free space .

One amp is defined as the current producing an attractive force of NUMBER@1 × NUMBER@2 -- NUMBER@3 Newton per metre of length between these wires .
