Question

Wires carrying current can attract or repel each other. two wires are parallel but carry current in opposite directions.

I1 = 5 A,

I2 = 8 A

Distance between wires = 30 cm

Find the force per unit length on either wire

A.) 3.4 x 10^-5 N attractive

B.) 2.7 x 10^-5 N repulsive

C.) 2.7 x 10^-5 N attractive

D.) 7.2 x 10^-5 N repulsive

E.) 7.2 x 10^-5 N attractive

Answer 1

Given the current carried by the wire 1 is I1 = 5A, the current carried by the wire 2 is I2 = 8A and the distance between the wires is r = 30cm. The force per unit length between the wires is given by,

So the magnitude of force per unit length on either wire is 2.7 x 10^-5N/m.

Since the wires carry currents in the opposite direction, the force is repulsve in nature.

Option B is the correct answer.

(NB: In the question, the unit of force per unit length is given as N, but it is actuallt N/m.)