JEE Main20198 Apr 2019Morning ShiftPhysicsMagnetic Effects of CurrentActual
A circular coil having N turns and radius r carries a current I . It is held in the X Z plane in a magnetic field B i ^ . The torque on the coil due to the magnetic field is:
Options
- AB π r 2 I N
- BB r 2 I π N
- CB π r 2 I N
- DZ e r o
Correct answer
A. B π r 2 I N
Step-by-step solution
Magnetic moment M → = N I π r 2 j ^ Torque τ → = M → × B → = N I π r 2 j ^ × ( B i ^ ) = B N I   π r 2   ( - k ^ )   N   m τ → = B N I   π r 2   N   m