Answer to Question #1758 in Electricity and Magnetism for aa

Question

Two wires of same length are placed parallel to each other at a distance of 0.65 metres from each other.
Calculate the ratio of the force they exert on each other assuming 10 amperes current in the first wire and 5 amperes in the second wire

Answer 1

Denote the current in the first wire as I₁ (10 amperes) and the current in the second wire as I₂ (5 amperes).

The force that act at the unit length is

F_u=μ₀/4π (2I₁ I₂)/r=10^-7 *2*10*5 / 0.65=153.84*10^-7 N.