question_answer

Two thin, long, parallel wires, separated by a distance d carry a current of i ampere in the same direction. They will       [AIEEE 2005]

A) attract each other with a force of\[\frac{{{\mu }_{0}}{{i}^{2}}}{(2\pi d)}\]

B) repel each other with a force of\[\frac{{{\mu }_{0}}{{i}^{2}}}{(2\pi d)}\]

C) attract each other with a force of\[\frac{{{\mu }_{0}}{{i}^{2}}}{(2\pi {{d}^{2}})}\]

D) repel each other with a force of\[\frac{{{\mu }_{0}}{{i}^{2}}}{(2\pi {{d}^{2}})}\]

Correct Answer: A

Solution :

[a] The force per unit length between the two wires is

The force will be attractive as direction of current in both the conductors are same.