question_answer

Two long straight wires are set parallel to each other at separation r and each carries a current I in the same direction. The strength of the agnetic field at any point midway between the two wires is:

A) \[\frac{{{\mu }_{{}^\circ }}I}{\pi r}\]                           

B) \[\frac{2{{\mu }_{{}^\circ }}I}{\pi r}\]

C) \[\frac{{{\mu }_{{}^\circ }}I}{2\pi r}\]                         

D) \[Zero\]

Correct Answer: D

Solution :

[d] \[{{B}_{1}}=\frac{{{\mu }_{{}^\circ }}I}{2\pi \left( \frac{d}{2} \right)}\otimes \,into\text{ }the\text{ }plane\] \[{{B}_{2}}=\frac{{{\mu }_{{}^\circ }}I}{2\pi \left( \frac{d}{2} \right)}\odot \,into\text{ }the\text{ }plane\] \[{{B}_{net\,}}={{B}_{1}}-{{B}_{2}}\] \[=0\]