Why did original analog television sets contain a copper coil?

Answer 1

As a electronic magnet that directs the beam of electrons to swipe the screen from top to bottom. This beam would light up the phosphor dots that made up the screen to either glow, or remain dark. Each frame or complete picture was made up of odd or even spots, and would interlace the screen for 30 frames per second. Our eyes would see a complete picture, but actually at any given moment, the screen was lit up with only 1 dot.