Behaviour of Current Loop in a Magnetic Field
Category : JEE Main & Advanced
(1) Torque : Consider a rectangular current carrying coil PQRS having N turns and area A, placed in a uniform field \[\overrightarrow{B},\] in such a way that the normal \[(\hat{n})\] to the coil makes an angle \[\theta \] with the direction of \[\overrightarrow{B}\]. The coil experiences a torque given by \[\tau =NBiA\sin \theta \]. Vectorially \[\overrightarrow{\tau }=\overrightarrow{M}\times \overrightarrow{B}\]
(i) \[\tau \] is zero when \[\theta =0,\] i.e., when the plane of the coil is perpendicular to the field.
(ii) \[\tau \] is maximum when \[\theta ={{90}^{o}}\], i.e., the plane of the coil is parallel to the field \[{{\tau }_{\max }}=NBiA\]
(2) Workdone : If coil is rotated through an angle \[\theta \] from it's equilibrium position then required work. \[W=MB(1-\cos \theta ).\] It is maximum when \[\theta ={{180}^{o}}\Rightarrow {{W}_{\max }}=2MB\]
(3) Potential energy : \[U=-MB\cos \theta \Rightarrow U=-\overrightarrow{M}.\overrightarrow{B}\]
You need to login to perform this action.
You will be redirected in
3 sec
