Question

Cathode rays are produced only when the pressure of the gas inside the discharge tube is very very low. Give reason

Answer 1

Low pressure maintained in the cathode ray tube while performing a cathode ray experiment was to minimize the influence of gaseous ionization present in the discharge tube and then to observe the anticipated deflection of the cathode rays by means of an electric field.

If the tube is not evacuated, then there would be excessive ionization of the gas present in the discharge tube, thus offsetting the effect of the electric field in deflecting cathode rays.

Hence Cathode rays are produced only when the pressure of the gas inside the discharge tube is very low.