Question

Two long parallel current-carrying conductors are 0.4 m apart in air and carry currents 5 A and 10 A. Calculate the force per metre on each conductor, if the currents are (a) in the same direction and (b) in the opposite direction.

Answer 1

Data: s = 0.4 m, I₁ = 5 A, I₂ = 10 A, μ₀/4π = 10⁻⁷ N/A²

The force per unit length acting on each conductor is

`F/l = ((μ_0)/(4π)) (2I_1I_2)/s`

= (10⁻⁷ N/A²) `(2(5 A) (10 A))/(0.4 m)`

= 2.5 × 10⁻⁵ N/m

= 25 μN/m

This force is attractive if the currents are in the same direction and repulsive if the currents are in the opposite directions.