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The photoelectric effect is the emission of electrons from a material caused by electromagnetic radiation such as ultraviolet light. Electrons emitted in this manner are called photoelectrons. The phenomenon is studied in condensed matter physics, solid state, and quantum chemistry to draw inferences about the properties of atoms, molecules and ...
Hallwachs was a known as a builder of scientific instruments. Among the devices he invented are the electrometer quadrant and a double refractometer of great precision. Hallwachs was an assistant of Heinrich Hertz, in 1886, before the photoelectric effect was discovered. Hallwachs and Hertz, in 1887, carried on the investigations of ...
[64]: 231–236 In 1905, Albert Einstein published the theory of the photoelectric effect. It appeared that the only possible explanation for the effect was the quantization of light itself. Later, Niels Bohr showed that atoms could only emit discrete amounts of energy.
Photoemission or photoelectric effect: Photons cause electrons to transition from the conduction band of a material to free electrons in a vacuum or gas. Thermal: Photons cause electrons to transition to mid-gap states then decay back to lower bands, inducing phonon generation and thus heat.
Built the first solar cell based on the outer photoelectric effect and estimated the response time of the photoelectric current. Discovered the decrease of the solar cell's sensitivity with time (fatigue of solar cells). Other. Calculated the proportion between electrodynamic and electrostatic units, producing a value very close to the speed of ...
However, the later discovery of the photoelectric effect demonstrated that under different circumstances, light can behave as if it is composed of discrete particles. These seemingly contradictory discoveries made it necessary to go beyond classical physics and take into account the quantum nature of light.
Willoughby Smith (6 April 1828, in Great Yarmouth, Norfolk – 17 July 1891, in Eastbourne, Sussex) was an English electrical engineer who discovered the photoconductivity of the element selenium. This discovery led to the invention of photoelectric cells, including those used in the earliest television systems.
It was invented by John N. Shive at Bell Labs in 1948 [6]: 205 but it was not announced until 1950. [7] The electrons that are generated by photons in the base–collector junction are injected into the base, and this photodiode current is amplified by the transistor's current gain β (or h fe). If the base and collector leads are used and the ...