Investigating The properties Of Electrons

An electron gun is used to investigate the properties of electron beam.The electrons are produced by the thermionic emission from a tungsten filament heated by 6V supply.A high positive potential is applied to cylindrical anode (+).The electrons are accelerated to a high speed and pass through the hole of the anode in the form of a fine beam of electrons.The whole set up is fitted in an evacuated glass bulb.

Deflection Of Electrons By Electric Field:-

We can set up electric field by applying a potential difference across two parallel metal plates placed horizontally separated by some distance.When an electron beam passes between the two plates ,it can be seen that the electrons are deflected toward the positive plate.The reason for this is that electrons are attracted by the positive charges and are repelled by the negative charges due to force F=qE,where 'q' is the electron charge and 'E' is the electron field due to plates.The degree of deflection of electrons from their original direction is proportional to the strength of the electric field applied.
Deflection Of Electrons By Magnetic Field:-Now we apply magnetic field at right angle to the beam of electrons by using a horseshoe magnet.We will notice that the spot of the electrons beam on the screen is getting deflected from its original direction.Now change the direction of horseshoe magnet.We will see that spot on the fluorescent screen is getting deflected in the opposite direction.