✔ 最佳答案
CRT (Cathode Ray Tube) works by a beam of electrons, emitted from an electron gun, striking on a fluorsecent screen. Phosphor on the screen is then excited by the energetic electrons and gives out visible light.
Since the elctrons, on striking the screen, undergo a decceleration. According to classical electromagnetic theory, part of the kinetic energy of the electrons will turn into electromagnetic waves. Given the operation energy of electrons in a typical CRT of about 10 keV, soft X-rays will be produced.