Why does the charge-to-mass ratio of positive rays depend on the residual gas in the discharge tube? Why is the charge-to-mass ratio of all cathode rays the same?
In case of positive rays, the ions remaining after the loss of electrons might have the same magnitude of charge, but different masses. Hence, they will have different charge to-mass ratio. Cathode rays are made up of electrons and all electrons have same charge to-mass ratio. That’s why charge to mass ratio of all cathode rays is same.