A wire with a weight per unit length of 0.075 N/m is suspended directly above a second wire. The top wire carries a current of 29.2 A and the bottom wire carries a current of 59.1 A. Find the distance of separation between the wires so that the top wire will be held in place by magnetic repulsion.

force between two current carrying conductor per unit length

= (μ₀ / 4π) x (2 i₁i₂ / R), i₁ and i₂ be current in them, R is distance between two,

= 10⁻⁷ x 2 x 29.2 x 59.1 / R.

This force balances weight of wire per unit length

= 10⁻⁷ x 2 x 29.2 x 59.1 / R. =.075

= 10⁻⁷ x 2 x 29.2 x 59.1 /.075 = R

R = 4.6 x 10⁻³ m

4.6 mm.