A thin flexible wire of length L is connected to two adjacent fixed points and carries a current I in the clockwise direction, as shown in the figure. When the system is put in a uniform magnetic field of strength B going into the plane of the paper, the wire takes the shape of a circle. The tension in the wire is :

Options

A. IBL
B. `(IBL)/(pi)`
C. `(IBL)/(2pi)`
D. `(IBL)/(4pi)`

Answer

C

Explanation

`L=2pir,:.R=L/(2pi),2Tsin(d theta)=d theta`
For small angles, `sin (d theta)=d theta`
`:.2T(d theta)=I(dL)Bsin90^@,=I(2Rd theta).B`
`:.T=IRB=(ILB)/(2pi),:.` Correct option is (c)