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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.
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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