Question

A particle moves in a circle of diameter 1.0cm under the action of a magnetic field of 0.40T. An electric field of 200V/m makes the path straight. Find the charge/mass ratio of the particle.

Answer 1

r = 0.5cm = 0.5 × 10^–2m

B = 0.4T, E = 200V/m

The path will straighten, if qE = quB => E = (rqB X B)/m  [∴ r = mv/qB]

=> E = rqB²/m => q/m = E/B²r = 200/(0.4 x 0.4 x 0.5 x 10^-2) = 2.5 x 10⁵c/kg