Question

Find time period of a bar magnet osciallating freely in a uniform magnet field vector B.

Answer 1

(i) As the magnetic force α F_m(= qvB) provides the necessory centripetal force (= mv²/r) to the charged particle to move in a circle.

qvB = mv/r

or Radius of path.

r = mv/qB

For a given charge, mass and magnetic field r ∝ v. This means that fast particle moves in large circles and slow ones in small circles. 

(ii) The time period of revolution of the charged particle in the magnetic field is