The unit of ele. current 'AMPEAR' is the current which when flowing through each of two parallel wires spaced 1 meter apart in vaccum and of infinite length will give rise to a force between them equal to .................... N/m.
Options:
(a) 1
(b) `2 xx10^(-7)`
(c) `1xx 10^(-2)`
(d) `4xx 10^(-7)`