Infrared Eye


To demonstrate emission of infrared radiation from a hot source, and to show an application of the photoelectric effect.


Infrared Eye with hot plate.


Setup Time

5 min.




    The "Infrared Eye" uses an imaging tube to convert infrared radiation into a visible image. A hot plate◙provides a convenient source of infrared radiation which glows brightly when viewed with the naked eye. The imaging tube works by the photoelectric effect: infrared photons are absorbed on the front surface of the imaging tube, producing photoelectrons; the photoelectrons are accelerated to strike a fluorescent screen at the back of the tube, causing it to glow visibly. ◙This device is not sensitive enough to pick up heat from the human body, but easily sees the radiation emitted by the tra