Discovery of Electrons (Cathode Rays)

Discovery of Electrons (Cathode Rays)

• A gas discharge tube is fitted with metal electrodes known as cathode and anode.
• This glass tube is filled with Gas.The Electrodes are connected with high voltage battery.
• The exact voltage required depend upon the length of glass tube and pressure of gas inside tube.
• A vacuum pump is attached to glass side from a side in order to decrease pressure of gas inside tube.
• It is observed that current does not flow through gas at ordinary pressure.
• When pressure of Gas is reduced to 0.01 torr and high current of 5000-10000 voltages is applied,electric discharge takes place through the gas.
• Some rays are produced which creates greenish fluorescene on the walls of glass tube.
• As these rays were produced from Cathode they were named as "cathode rays".
• The colour of glow or fluorescene produced on the walls of glass depends upon the composition of glass.