Question

An electron enters a region where magnetic induction B and electric field E are mutually perpendicular to one another then

• A. it will always move in the direction of B.
• B. it will always move in the direction of E.
• C. it always possessses circular motion.
• D. it can go undeflected also.

Answer 1

The correct option is D it can go undeflected also.

When electrons enter in a region where there is only magnetic field, then force exerted by the magnetic field will deflect the electron in a direction perpendicular to its motion and also perpendicular to the magnetic field.

Whereas in the presence of electric field, force exerted by the electric field is in a direction opposite to the direction of electric field. As a result, electron deflected by magnetic field is nullified by the deflection by electric field. As a result, electron moves undeflected.