question_answer

An arbitrary shaped closed coil is made of a wire of length L and a current I ampere is flowing in it. If the plane of the coil is perpendicular to magnetic field \[\overset{\to }{\mathop{B}}\,\], the force on the coil is [MP PMT 2001]

A)            Zero                                         

B)            IBL

C)            2IBL                                          

D)            \[\frac{1}{2}IBL\]

Correct Answer: A

Solution :

                   As shown in figure, since \[\overrightarrow{L}=0\]                    Hence according to \[\vec{F}=i(\vec{L}\times \vec{B})\] Þ \[\vec{F}=0\]