Two thin, long, parallel wires, separated by a distance 'd' carry a current of 'i' A in the same direction. They will

Options

A. repel each other with a force of `mu_0i^2//(2pid)`
B. attract each other with a force of `mu_0i^2//(2pid)`
C. repel each other with a force of `mu_0i^2//(2pid^2)`
D. attract each other with a force of `mu_0i^2//(2pid^2)`

Answer

B

Explanation

(b)`F/l = (mu_0i_1i_2)/(2pid) = (mu_0i^2)/(2pid) `

(attractive as current is in the same direction).