# 4.18 c) An electron travelling west to east enters a chamber having a uniform electrostatic field in north to south direction. Specify the direction in which a uniform magnetic field should be set up to prevent the electron from deflecting from its straight line path.

The electron is moving towards the east and has a negative charge therefore $q\vec{V}$ is towards the west direction, Force will be towards south direction if the magnetic field is in the vertically downward direction as $\vec{F}=q\vec{V}\times \vec{B}$