Q. $A,\ B$ and $C$ are parallel conductors of equal length carrying currents $I,\ I$ and $2I$ respectively. Distance between $A$ and $B$ is $x$. Distance between $B$ and $C$ is also $x$. $F_{1}$ is the force exerted by $B$ on $A$ and $F_{2}$ is the force exerted by $C$ on $A$. Choose the correct answer
A) $F_{1} = 2F_{2}$
B) $F_{2} = 2F_{1}$
C) $F_{1} = F_{2}$
D) $F_{1} = - F_{2}$
Explanation
(d) $F = \frac{\mu_{0}}{4\pi}\frac{2l^{2}}{a}$
$F_{1} = \frac{\mu_{0}}{4\pi}.\frac{2i^{2}}{x}$ [Attraction]
$F_{2} = \frac{\mu_{0}}{4\pi}\frac{2i \times 2i}{2x} = \frac{\mu_{0}}{4\pi}\frac{2i_{2}}{x}$ [Repulsion]
Thus $F_{1} = - F_{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.