ICSE Class 9 Answered

Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. At that time, It was known that electron is negatively charged. Experiment was to confirm the ammount of charge by e/m ratio. So, negative electrons are attracted by anode so fluoroscent screen is applied to near anode.

 

But whenever we talk about discovery of electron, We include onl;y cathode ray tube experiments only. Because other experminets were notaccuirate and were based on assumptions.