Answer the following question:
An electron travelling west to east enters a chamber having a uniform electrostatic field in the 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.
Answer the following question:
An electron travelling west to east enters a chamber having a uniform electrostatic field in the 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.

Because of the electric field, the negatively charged electron tends to go towards the north. The electron will not be deflected if an equal magnetic force acts in the other direction. We derive the direction of the magnetic field along the vertically downward direction using Fleming’s left-hand rule and using the conventional direction of charge flow from east to west.