The gun scans the florescent screen of the TV from left to right and top to bottom ( just similar ). The tiny specks glow on for on instant. A bright speck when there are more electrons.Duller speck when there are fewer electrons. This exactly reverses what happens in the camera. TV breaks up a picture into tiny specks of light. These specks are converted into electric current.The current is in the form of electro-magnetic waves. These travel, and enter the TV to be converted back into specks of light. These specks form the original picture pattern.