question_answer

A current of \[1\,\,A\] is passed through a straight wire of length\[20\,\,m\]. The magnetic field at a point air at a distance of \[3\,\,m\] from either end of wire and lying on the axis of wire will be

A) \[\frac{{{\mu }_{0}}}{2\pi }\]                                      

B) \[\frac{{{\mu }_{0}}}{4\pi }\]

C)  \[\frac{{{\mu }_{0}}}{8\pi }\]                                     

D)  \[zero\]