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Question
What are cathode rays? Why are they called ‘cathode rays’? Name a material which exhibits fluorescence when cathode rays fall on it.
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Solution
Cathode rays are the stream of negatively charged particles called electrons. They are called cathode rays because they are given out from cathode in a discharge tube operating at about 10,000 V when the pressure inside the tube is about 0.01 mm of Hg. Zinc Sulphide exhibits fluorescence when cathode rays fall on it.
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