What is the purpose of the graphite coating in a cathode ray tube? Is it applied on the inside or outside?

Question

Also, what is the purpose of a shadow mask?
Thanks for your answer.

Answer 1

The graphite is called aquadag. It is a coating on the inside of the tube, and it acts as the positive electrode (anode) to pick up the electron current after the electrons have 'done their thing' in lighting up the phosphors (red, green, blue, or 'white' for b/w TVs). Since there is basically a distribution of electrons across the inside face of the tube, they will move to the outside, to the aquadag, and to the anode button on the outside of the tube.

The shadow mask also collects electrons and routes them to the outside, but it also serves to limit secondary electron 'hits' or 'bouncing' to the phosphors that would cause 'blooming'.

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Answer 2

There is a florosent coating there so that it absorb the light and give us a image.
Shadow masking is finer holes in which light is crossed.