Physics

Problem

Which one of the following gives the magnitude of the magnetic force per unit length between two long, straight, parallel wires carrying currents

I_1

and

I_2

separated by a distance

d

in vacuum? a)

\dfrac{\mu_0 I_1 I_2}{\pi d}

\dfrac{\mu_0 I_1 I_2}{2\pi d}

\dfrac{\mu_0 I_1 I_2}{4\pi d}

\dfrac{\mu_0 I_1 I_2}{2 d}