Question

Two long and parallel straight wires A and B carrying currents of 8.0 A and 5.0 A in the same direction are separated by a distance of 4.0 cm. Estimate the force on a 10 cm section of wire A.

Answer 1

Current flowing in wire A, I_A = 8.0 A

Current flowing in wire B, I_B = 5.0 A

Distance between the two wires, r = 4.0 cm = 0.04 m

Length of a section of wire A, l = 10 cm = 0.1 m

Force exerted on length l due to the magnetic field is given as:

Where,

= Permeability of free space = 4π × 10^–7 T m A^–1

The magnitude of force is 2 × 10^–5 N. This is an attractive force normal to A towards B because the direction of the currents in the wires is the same.