question_answer

Two long straight wires are set parallel to each other at separation rand each carries a current\[i\] in the same direction. The strength of the magnetic field at any point midway between the two wires is

A)  \[\frac{{{\mu }_{0}}i}{\pi r}\]               

B)  \[\frac{2{{\mu }_{0}}i}{\pi r}\]

C)  \[\frac{{{\mu }_{0}}i}{2\pi r}\]

D)  zero

Correct Answer: D

Solution :

\[{{B}_{1}}=\frac{{{\mu }_{0}}i}{2\pi \left( \frac{r}{2} \right)}\]                 \[{{B}_{2}}=\frac{{{\mu }_{0}}i}{2\pi \left( \frac{r}{2} \right)}\] So, \[{{B}_{net}}=0\]