The photoelectric effect was discovered in 1887 by the German physicist Heinrich Rudolf Hertz. While working on radio waves, Hertz observed that, when ultraviolet light shines on two metal electrodes with a voltage applied across them, the light changes the voltage. Sparking normally takes place at the time.

If asked, how did Albert Einstein note what happened with the photoelectric effect?

Einstein won the Nobel Prize for Physics not for his work on relativity, but for explaining the photoelectric effect. He proposed that light is made up of packets of energy called photons. The photoelectric effect occurs when light shines on a metal. Light of any frequency will cause electrons to be emitted.

Einstein specifically described the photoelectric effect using a formula that relates the maximum kinetic energy (Kmax) of the photoelectrons to the frequency of the absorbed photons (ƒ) and the threshold frequency (ƒ0) of the photo emissive surface.

Einstein directly said that when charge (e) is given in coulombs, the energy will be calculated in joules. When charge (e) is given in elementary charges, the energy will be calculated in electron volts. This results in a lot of constants. One can use the method that is most appropriate to solve the problem (handle the situation).

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