The circular current loop of radius b shown in Fig. is mounted rigidly on the axle, midway between the two supporting cords. In the absence of an external magnetic field, the tensions in the cords are equal and are `T_0.`
a. What will be the tensions in the two cords when the vertical magnetic field B is present?
b. Repeat if the field is parallel to the axis.

Answer

A, B, D

Explanation

(a)`T_(0)=(mg)/2`
`T_(1)+T_(2)=mg=2 T_(0)`
`T_(2)1/2+pib^(2)iB=T_(1)1/2` (applying equation of torque about centre of mass)
`T_(1)=T_(0)+(pib^(2)iB)/l`
`T_(2)=T_(0)+(pib^(2)iB)/l`
(b) `B||"exist"`
`tau_(B)=0`
`T_(1)=T_(2)=T_(0)`