Question

1. Describe the parts of a discharge tube. Why must the pressure inside the tube be pumped almost to a vacuum to conduct electricity?

Answer 1

Part 1. Parts of Discharge tube cathode anode k Glass tube vacuum pump - '+ cathode in Metal plate which is connected to negative terminal of battery. . - ionization energy of cathode material should be low for easy escaping of electrons. Anode - Metal plate which is connected to positive terminal of battery. vacuum pump maintain the gas pressure inside the tube. Part 2 :- Why pressure inside the tube must be low, High pressure of gas inside the tube means more number of atoms of that gas inside the tube which is in accordance to the following formula PV = nRT so more number of atoms means more number of collisions with the electrons that mean more obstacle in movement of electrons or Lesser will be the conduction. Also electron may be used in knocking out more electrons. Additionally very high voltage is required to conduct electricity through the tube or we can say to move electons.