Q. A long wire $A$ carries a current of $10\ amp$. Another long wire $B$, which is parallel to $A$ and separated by $0.1m$ from $A$, carries a current of $5\ amp$, in the opposite direction to that in $A$. What is the magnitude and nature of the force experience per unit length of $B$ $(\mu_{0} = 4\pi \times 10^{- 7}weber/amp - m)$
A) Repulsive force of $10^{- 4}N/m$
B) Attractive force of $10^{- 4}N/m$
C) Repulsive force of $2\pi \times 10^{- 5}N/m$
D) Attractive force of $2\pi \times 10^{- 5}N/m$
Explanation
(a) $F = \frac{\mu_{0}}{4\pi}\frac{2i_{1}i_{2}}{a} = 10^{- 7} \times \frac{2 \times 10 \times 5}{0.1} = 10^{- 4}N\ \lbrack Repulsive\rbrack$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.