question_answer

If a current of \[i\] amp is flowing in the winding of solenoid and  ft is the number of turns per unit length, then the magnetic field at the centre of solenoid is

A)  \[{{\mu }_{0}}ni\]                          

B)         \[\frac{{{\mu }_{0}}ni}{2}\]

C)  \[\frac{{{\mu }_{0}}i}{2n}\]                        

D)         \[\frac{{{\mu }_{0}}i}{n}\]