If the magnetic field is parallel to the positive y-axis and the charged particle is moving along the positive x-axis (Fig.), which way would the Lorentz force be for (a) an electron (negative charge), (b) a proton (positive charge).

Explanation

The velocity v of particle is along the x-axis, while B, the magnetic field is along the y-axis, so `v x× B` is along the z-axis (screw rule or right-hand thumb rule). So, (a) for electron it will be along `–z` axis. (b) for a positive charge (proton) the force is along `+z` axis.