Which expression gives the magnitude of the force per unit length between two long

PHYSICS · Single correct · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism

Problem

Which expression gives the magnitude of the force per unit length between two long, straight, parallel wires separated by a distance

r

and carrying currents

I_{1}

and

I_{2}

? (a)

\displaystyle \frac{\mu_{0}}{4\pi}\,\frac{I_{1}I_{2}}{r^{2}}

(b)

\displaystyle \frac{\mu_{0}}{2\pi}\,\frac{I_{1}I_{2}}{r}

(c)

\displaystyle \frac{\mu_{0}}{2\pi}\,\frac{I_{1}I_{2}}{r^{2}}

(d)

\displaystyle \frac{\mu_{0}}{2\pi}\,\frac{I_{1}+I_{2}}{r}