Question

The final torque on a coil having magnetic moment 25 A m2 in a 5 T uniform external magnetic field, if the coil rotates through an angle of `60^(@)` under the influence of the magnetic field is
A. 216.5Nm
B. 108.25Nm
C. 102.5Nm
D. 258.1Nm

Answer 1

Correct Answer - B
`|vec(tau)|=|vecmxxvecB|=mBsin theta`
Here, `m=25Am^(2),theta=60^(@),B=5T`
`therefore" "tau=25xx5xxsin 60^(@) or tau=125xx(sqrt3)/(2)=108.25" N m"`