Today we have to delve a little deeper into the nature of light. Since according to various studies throughout history, it can sometimes behave like particles and others like waves. Since light is electromagnetic radiation that affects vision and is distinguished from other electromagnetic radiation in its amount of energy.
LIGHT AS A WAVE
According to wave theory, the energy of an electromagnetic wave is distributed in the same way between electric and magnetic fields that are perpendicular. And that also oscillate perpendicular to the direction of propagation of the waves, as we can see in the following figure.
In the year 1801 the first demonstration that light had wave behavior was given by Thomas Young. He demonstrated that light exhibited interference behavior when appropriate conditions were present. But it was in the year 1873 when the most important finding in this field was demonstrated, James Clerk Maxwell proved that light was not only a wave, but specifically, it was an electromagnetic wave with a very high frequency. He predicted that the speed of these waves was approximately 3 × 10 ^ 8 in a vacuum. A few years later, in 1887, Hertz corroborated what Maxwell said experimentally, producing and detecting electromagnetic waves. In addition, it went a little further, and showed that these waves behave like any type of wave, that is, they have all the characteristics that waves possess, among others,
LIGHT AS A PARTICLE
Many of the properties of light were described thanks to its behavior as a wave, however, there were some experiments that led to an inconsistency with respect to waves. One of these experiments was the photoelectric effect, which consists of an emission of electrons from a metal surface that is exposed to light. (This method is used today to transform the Sun’s energy into electrical energy.)
Returning to the problem that arose due to the photoelectric effect, it was Einstein who solved it by contributing a new theory in which he used a concept developed by Max Planck; whereby atoms absorb and emit a quantity of energy called photons (which is a characteristic of matter). Einstein considered that the energy of electromagnetic waves (light) traveled in packages called quanta or photons.
This relationship on the energy of light is represented in the following equation: Where E is the energy of the photon that is measured in Joules; v is the frequency of the wave mediated in Hertz (Hz); and h is called the Planck constant
, which expresses the relationship between the amount of energy and frequency that is associated with a quantum or a particle; its value is 6,626 × 10 ^ -34 Joules Hz.
Once it has been seen that light behaves both as a wave and as a particle, a new question arose, does only light have this dual behavior? That is, will there be any particle that also behaves as a wave?
The person in charge of studying this new challenge was Louis de Broglie using the results of his predecessors as Planck or Einstein, among others. Broglie determined that every particle can behave like a wave in concrete experiments. Therefore, each particle has an associated wave called the matter wave , and which gives all matter a dual behavior.
This behavior is characterized by the associated wavelength , λ = h / p, where h is the Planck constant already mentioned above and p is the momentum of the particle (p = mv).
In later experiments, Broglie was found to be correct. Unfortunately, it is not possible to appreciate this behavior in macroscopic particles.