question_answer

Two long straight wires are set parallel to each other. Each carries a current in the same direction and the separation between them is 2r. The intensity of the magnetic   field   mid-way between them is

A)  \[\frac{{{\mu }_{0}}i}{r}\]

B)  \[\frac{4{{\mu }_{0}}i}{r}\]

C)  zero             

D)  \[\frac{{{\mu }_{0}}i}{4r}\]

Correct Answer: A

Solution :

At point P, \[{{B}_{net}}={{B}_{AB}}+{{B}_{CD}}\] \[=\frac{{{\mu }_{0}}i}{2r}+\frac{{{\mu }_{0}}i}{2r}\] \[=\frac{{{\mu }_{0}}i}{r}\]