Devices in this collection of photocells include a Westinghouse Photo-electric cell, a Rank Cintel VA 26 photocell, several photomultipliers, and some Plumbicon television camera tubes. Each uses the photoelectric effect in its operation.

The photoelectric effect describes an interaction between photons and electrons. When light falls onto a material, if the light is of a high enough frequency, its energy can be absorbed by the surface electrons of the material. When this occurs, the electrons become energised and can escape from the surface. These devices use a combination of a negative photocathode and positive anode in a vacuum.The light ejects electrons from the photocathode that are then collected by the anode to generate an electric current.

Devices like the Cintel VA26 are responsible for the first sound-on-film processes used in movie making -as the film strip runs, light is shone through its edge. This edge has a transparent band that widens and narrows. As the light intensity varies, it is detected by a photocell and is translated into the appropriate sound by a loudspeaker. A photomultiplier has an inbuilt amplifier that multiplies every electron released by the photocathode into a pulse of millions and allows the detection of individual light quanta, called photons.

In 1905, Albert Einstein published his Annus Mirabilis papers, one of which discussed the Photoelectric effect and its relationship with the quantum nature of photons. For this work Einstein received the 1921 Nobel Prize (In the year 1922, however, due to delays). Robert Millikan confirmed this experimentally and later received the 1923 Nobel Prize for his work on the photoelectric effect and the elementary charge of electricity.

This item is part of the UQ Physics Museum ‘2015, International Year of Light’ Tour
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  • RCA Radiotron UX867 photocell 
  • RCA Radiotron 929 photocell 
  • Rank Cintel VA 26 photocell 
  • Cintel VB 39 photocell 
  • RCA 5819 photomultiplier 
  • Mullard 58CG photocell 
  • Photomultiplier with Venetian blind electron multiplier 
  • Venetian blind electron multiplier 
  • Dumont 6292 photomultiplier 
  • Westinghouse Photo-electric cell 
  • Philips Plumbicon television camera tube 
  • Philips 920 dual photcell 
  • Demonstration photocell