Question

A thin uniform rod of negligible mass and length l is attached to the floor by a hinge P. The other end is connected to a spring of force constant k. Rod is in a uniform magnetic field B pointing inwards the plane of paper. A current I is passed through the rod. Find the torque acting on the rod due to magnetic force when the rod makes an angle 53⁰ as shown in

• A. II²B
• B. $\frac { \mathrm { I } l ^ { 2 } } { 2 }$B
• C. $\frac { 3 \mathrm { I } l ^ { 2 } \mathrm {~B} } { 5 }$
• D. $\frac { 4 } { 5 }$II²B

Answer 1

Answer: (B)

$\frac { \mathrm { I } l ^ { 2 } } { 2 }$B

Answer 2

F = kx = IlB t =$\int \mathrm { d } \tau$==