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Planck's quantum theory and Photoelectric EffectWhat applications have been made from...

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ling04 | Student | eNoter

Posted September 10, 2011 at 11:47 AM via web

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Planck's quantum theory and Photoelectric Effect

What applications have been made from using the concepts of planck's quantum theory and ensteins photoelectric effect? For photoelectric effect i found that solar cells were made. Does anyone know in detail where these two ideas have been used in applications?

 

Also what kind of interactive activity can you do with a small group if you were trying to teach them these two concepts? Thanks

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valentin68 | College Teacher | (Level 3) Associate Educator

Posted October 27, 2013 at 6:23 AM (Answer #2)

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A good example of one application in which both photoelectric effect and quantum Planck theory are used together is the CCD (charge coupled device) TV camera. Basically the CCD camera is composed of an array of photoelectric sensors that under the action of external light produce an electric current. This happens because of the internal photoelectric effect which is a slightly modified version for semiconductors of the original external photoelectric effect for metals. As said, each element from the array of sensors in a CCD camera act as a tiny solar cell. To collect the electric charges that build up, the elements are connected in series and scanned in rows one after each other (thus the name of charge coupled devices), much like one reads the words from a book, by an electronic circuit that works based on physical phenomena demonstrated by the Planck quantum theory. The charge produced is moved from one device to the next one and so on, until it emerges in a circuit outside the CCD camera itself.

 To continue with examples of applications of photoelectric effect and Planck quantum theory, the night vision devices used by the military are another good example. At the lowest level, these night vision devices are small TV cameras having very sensitive photoelectric devices (which can function at high light wavelengths - the infrared spectrum). In the initial versions of these devices each incoming photon was producing an electron, which by electric multiplication (in high electric fields) was producing in turn many photons by striking a light emitting screen thus amplifying the light. In modern versions an electronic circuit working on ideas derived from the Planck quantum theory is amplifying the electric current produced by the infrared detectors.

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