![enter image description here](https://i.stack.imgur.com/6drQ1.png)

1.One of the observations I learned was that the glass tube begins to glow with a brilliant green light. Many websites I read through refer to a fluorescent material. However, as shown in the above diagram there was no fluorescent material in the experiment carried out first on the cathode ray tube. **So where does the green glow come from. Is this the color of the radiation itself?**

2."*Cathode rays travel in straight lines. That is why, cathode rays cast shadow of any solid object placed in their path. The path cathode rays travel is not affected by the position of the anode.*" I just can't seem to understand this explanation of the one of the observations.Also, different websites analyses this observation differently. For example, " *The cathode rays consist of material particles because they produced shadow of objects placed in the way*"

3.Two of the conditions of the experiment were air at very low pressure and secondly a very high potential difference. Could someone please tell me why these conditions were necessary?

I know the questions are very silly but because different websites refer to different things, I am becoming confused with something that should be simple to understand.