3) a cathode ray tube (crt) is a device that produces a focused beam of electrons in a vacuum. the electrons strike a phosphor-coated glass screen at the end of the tube, which produces a bright spot of light. the position of the bright spot of light on the screen can be adjusted by deflecting the electrons with electrical fields, magnetic fields, or both. although the crt tube was once commonly found in televisions, computer displays, and oscilloscopes, newer appliances use a liquid crystal display (lcd) or plasma screen. you still may come across a crt in your study of science. consider a crt with an electron beam average current of 25.00î¼a. how many electrons strike the screen every minute?