Q. $AB$ and $CD$ are long straight conductors, distance $d$ apart, carrying $a$ current $I$. The magnetic field at the midpoint of $BC$ is
A) $\frac{- \mu_{0}I}{2\pi d}\widehat{k}$
B) $\frac{- \mu_{0}I}{\pi d}\widehat{k}$
C) $\frac{- \mu_{0}I}{4\pi d}\widehat{k}$
D) $\frac{- \mu_{0}I}{8\pi d}\widehat{k}$
Explanation
(b) The field at the midpoint of $BC$ due to $AB$ is $\left( - \frac{\mu_{0}}{4\pi}.\frac{i}{d/2}\widehat{k} \right)$ and the same is due to $CD$. Therefore the total field is $\left\lbrack - \left( \frac{\mu_{0}i}{\pi d} \right)\widehat{k} \right\rbrack$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.