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

DESCRIPTION: 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 transmitters for the hearing impaired in the lecture halls.

The switch closest to the eyepiece is ON/OFF and the other switch is for an infrared lamp mounted above the lens. The focus works in the 2ft-6ft range unless the lens is stopped down.



EQUIPMENT: Infrared Eye with hot plate.

SETUP TIME: 5 min.

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