A cathode ray tube (CRT) is a device that produces cathode rays (a stream of electrons).
The inside of the tube is evacuated or filled with a noble gas. When a high voltage is applied to the cathode ray tube, electrons are ejected from the cathode and accelerated toward the anode. Some of the cathode rays can escape through the open hole in the anode. Cathode rays go straight if there is no influence from the environment.
In 1897, British physicist Thomson discovered that this flow was composed of negatively charged particles from the following phenomenon.
- If there is a metallic object in the middle, it will block the flow and create a shadow.
- Cathode rays bend in a magnetic field in the opposite direction to that of the current.
- Cathode rays are attracted to the (+) of the electric field.
Before flat-screen televisions became widespread, fluorescent materials were applied to the end of the cathode ray to emit light, and it was used as a display. (CRT Display)