cathode rays do not depend on the nature of gas or the anodes whereas the canal rays do.why?

Asked by  | 2nd Sep, 2011, 12:00: AM

Expert Answer:

Positive rays are sometimes known as the canal rays. If the cathode of a discharge tube has holes in it and the pressure of the gas is around 10–3 mm of Hg then faint luminous glow comes out from each hole on the backside of the cathode. It is said to be the positive rays which are coming out from the holes. Hence canal rays are positive ions having same mass if the experimental gas does not have isotopes. However if the gas has isotopes then positive rays are group of positive ions having different masses.

But q /m ratio of these rays depends on the nature of the gas in the tube (while in case of the cathode rays q/m is constant and doesn't depend on the gas in the tube).

Whereas the cathode rays in the discharge tube are the electrons produced due to ionization of gas and that emitted by cathode due to collision of positive ions and are hence independent of nature of gas.

Answered by  | 7th Sep, 2011, 10:56: AM

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