Physics (AS & A Level) · May / June 2017 · Paper 43 · Question 7

An electron having charge –q and mass m is accelerated from rest in a vacuum through a potential difference V. The electron then enters a region of uniform magnetic field of magnetic flux density B, as shown in Fig. 7.1. path of electron uniform magnetic field into plane of paper Fig. 7.1 The direction of the uniform magnetic field is into the plane of the paper. The velocity of the electron as it enters the magnetic field is normal to the magnetic field. The radius of the circular path of the electron in the magnetic field is r.

Read automatically from the paper; the printed page above is exact.