A neutron, a proton, an electron and an α-particle enter a region of uniform magnetic field with the same velocities. The magnetic field is perpendicular and directed into the plane of the paper. The tracks of the particles are labelled in the figure. The electron follows the track .....

Question

G1 Physics · Accepted Answer

Radius r=mv/(|q|B). The electron has the smallest m/|q| and negative charge, so it follows the tightest curve in the opposite sense to positive particles. In the figure that is track D. Hence D.