Question

Electrons moving with different speeds enter a uniform magnetic field in a direction perpendicular to the field. They will move along circular paths

(a) of the same radius

(b) with larger radii for the faster electrons

(c) with smaller radii for the faster electrons

(d) either (b) or (c) depending on the magnitude of the magnetic field

Answer 1

Correct Answer is: (b) with larger radii for the faster electrons

mv = BQr

or r = (m/BQ) v

As m, Q and B are the same for all the electrons, r ∝ v.