Question

what happens when electric field is applied to the path of cathode rays?

Answer 1

Cathode ray are steam of moving electrons. If we apply external electric field on it, there are three possibility.

1. Electric field is parallel to cathode ray

So, force on electron will be F = - eE.

That means electrons suffer from retarding force, so its velocity reduces.

2.Electric field is parallel to cathode ray

So, force on electron will be F = - e(-E). =eE

That means electrons get accelerating force, so its velocity increases.

3. Electric field is perpendicular to cathode ray

Electrons realise perpendicular force, and cathode ray deflected from its path.