The History of Photoelectric Effect

The phenomenon where electrically charged particles from the metal are emitted after it absorbs electromagnetic radiation is the definition of the photoelectric effect. The effect is described as electron ejection from a metal plate. It is one of the fundamental concepts in modern physics as it provides an answer to one of the most pressing questions in the world of science about light’s nature. Albert Einstein provided the answer in 1905, but Heinrich Rudolf Hertz found the photoelectric effect theory in 1887.

Early work and discovery

Before Albert Einstein explained the matter, several scientists made similar observations but were unable to clarify the concept. In the 1800s, James Clark Maxwell and Hendrik Lorentz of Scottish and Dutch origin resolved that light behaves like a wave. The theory was proven when light waves demonstrated interference, scattering, and diffraction. German physicist Heinrich Rudolf Hertz, in 1887, discovered the photoelectric effect. Regarding the theory of radio waves, Heinrich’s observation claimed that sparking takes place when two metal electrodes are shone with ultraviolet light, there is a voltage change because of the light.

In 1899, JJ Thompson discovered that if ultraviolet light is being hit on a metal surface, then it causes electron ejection. Another scientist Philipp Lenard, in 1902, clarified the connection between electricity and light, which further proved the theory of the photoelectric effect. There are further studies conducted on the subject that strengthened the connection between matter which can’t be explained by physics and light. This relation described light as an electromagnetic wave. Einstein conveyed that light is made up of small packets, which were initially called quanta but later named photons.

Theoretical studies were done by Arthur Compton in 1922 further proved that X-rays could be treated as photons. He earned the Nobel Prize in 1927 for the same. In 1931, Ralph Howard Fowler did theoretical studies to link photoelectric currents with metal temperatures.

Principles of the photoelectric effect

When the light of suitable frequency falls upon a metal surface, the emission of electrons takes on the surface. This phenomenon is known as the photoelectric effect. The electrons which are ejected from the metal surface are called photoelectrons. There is a current which is produced due to the emission of electrons, and the current is known as photocurrent. The photoelectric effect proves the quantum nature of radiation. However, the classical electromagnetic theory could not explain the photoelectric effect.

Application of photoelectric effect

Even though the photoelectric effect is theoretical, there are several practical applications of the effect. Originally utilised to detect light, photoelectric cells are used with a vacuum tube that contains a cathode that emits electrons. On the other hand, the anode is used to store the resulting current. Currently, these phototubes are used in fibre optics telecommunications and even solar cells. Imaging Technology is one of the popular applications of photomultipliers and photodiodes. Image intensifiers and television camera tubes utilise the theory of imaging technology. It is used to study several nuclear procedures and chemical analysis of materials, depending on the electrons emitted by them. Last but not least, it gives out information about the transition of atoms in electrons between different states of energy.

Conclusion

The photoelectric effect is the phenomenon where electrons are emitted from metal surfaces after they are exposed to the energy of light, visible light, or even UV rays of a preferable frequency. Photoelectrons are the electrons that are emitted by the photoelectric effect. Photoelectrons constitute a current known as the photoelectric current. Several studies have shown that nonmetals also display a photoelectric effect. Gases and liquids also show a limited photoelectric effect under ideal circumstances.