Two parallel wires separated by a distance of 10 cm carry currents of 10 A and 40 A along the same direction. Where should a third current be placed so that it experiences no magnetic force?

Question

Philoid · Accepted Answer

Let x be the distance of the wire W₃ from the wire carrying a current of 10A.

Magnetic force acting per unit length on a wire due to a parallel current-carrying wire is given by

In this case as the wire W₃ experiences no magnetic force.

∴ by wire w₁ = by wire w₂

⇒

⇒ 10 – x = 4x

⇒ x = 2 cm

Thus, wire W₃ is placed 2 cm from the 10 A current wire.