Question

The electron beam inside an old television picture tube is 0.40 mm in diameter and carries a current of 50 μA. What happens when this electron beam impinges on the inside of the picture tube screen?

1) The electron beam creates an image on the screen
2) The electron beam heats up the screen
3) The electron beam causes the screen to emit light
4) The electron beam damages the screen

Answer 1

When the electron beam inside an old television picture tube impinges on the screen, it causes the screen to emit light.

Step-by-step explanation:

When the electron beam inside an old television picture tube impinges on the inside of the picture tube screen, it causes the screen to emit light. This is due to the interaction between the beam and the phosphor-coated screen. The electrons in the beam collide with the atoms in the phosphor, exciting them and causing them to emit light.