question_answer

A small coil of N turns has an effective area A and carries a current I. It is suspended in a horizontal magnetic field \[\overrightarrow{B}\] such that its plane is perpendicular to \[\overrightarrow{B}\]. The work done in rotating it by \[180{}^\circ \] about the vertical axis is [MP PMT 1994]

A)            NAIB                                        

B)            2NAIB

C)            \[2\pi NAIB\]                       

D)            \[4\pi NAIB\]