CLASSIC AND MODERN THEORIES OF LIGHT
Introduction
Many people have asked themselves the same question as us what the hell is light? And they have responded in many ways, some better thought answers than others for example in the Middle Ages we believed we took rays through our eyes and with them we saw things what does not explain why we cannot see in the dark. But we are interested.
Developing
Classical theories
- Corpuscular theory
Par Isaac Newton, the light consisted of a flow of very small particles or corpuscles without mass, emitted by the light sources, which moved in a straight line with high speed. Because of this, they were able to cross the transparent bodies, which allowed us to see through them. On the other hand, in the opaque bodies, the twilight bounced, so we could not observe those behind.
This theory successfully explained the rectilinear propagation of light, refraction and reflection, but not Newton’s rings, interferences and diffraction. In addition, experiences carried out later allowed to demonstrate that this theory did not clearly clarify the nature of light.
- Undulating theory
Dutch scientist Christian Huygens, a contemporary from Newton, elaborated a different theory to explain the nature and behavior of light. This theory postulates that the light emitted by a source was formed by wave. In addition, it indicates that the speed of light decreases when penetrating water. With this, he explains and describes the refraction and laws of reflection.
In the beginning, this theory was not considered due to Newton’s prestige. It passed more than a century to be taken into account: it was subjected to tests through the work of the English doctor Thomas Young, about the light interference, and the French physicist Augustés Jean Fresnel, about the diffraction. As a consequence, it was clear that its explanatory power was greater than that of corpuscular theory.
- Electromagnetic theory
In the nineteenth century, the ideas of scientist JC Maxwell are added to the existing theories of the time. In this regard, he points out that each variation in the electric field produces a change in the proximity of the magnetic field and inversely. Therefore, light is a transverse electromagnetic wave that spreads perpendicularly to each other. This fact eliminated the idea that there was an intangible and invisible means of propagation, the ether, which was proven by Michelson and Morley’s experiment.
However, this theory leaves without explanation phenomena related to the behavior of light in terms of absorption and emission: the photoelectric effect and the emission of light by incandescent bodies. The above gives opportunity to the appearance of new explanations about light.
Modern Theories of Light
- Theory of how many
This theory proposed by the German physicist Max Planck establishes that the energy exchanges between matter and light are only possible for finite amounts or how many of light, which are subsequently called photons. The theory encounters the inconvenience of not being able to explain the undulating phenomena, such as interferences, diffractions, among others. We meet again with two opposite hypotheses, quantum and electromagnetic theory.
Some time later, based on Planck’s quantum theory, in 1905 the physicist of German origin Albert Einstein explained the photoelectric effect through the light corpuscles, which he called photons. With this he proposed that the light behaves as a wave under certain conditions.
- Undulating mechanics
This theory brings together electromagnetic theory and that of the many inherited from the corpuscular and undulating, which shows the double nature of light. The one who behaves as a wave and particle was reaffirmed by the French scientist Luis de Broglie, in 1924, which also added that the photons had a wave movement, that is, the light had a bi behavior. Thus, the light, in its propagation, acts as a wave, but its energy is transported adjacent to the light wave by small corpuscles called photons. This theory establishes, then, the corpuscular particularity of light in its interaction with matter (issuance and absorption procedure) and the electromagnetic nature of its propagation.
conclusion
We live among it, a strange thing that gives meaning to the shadows, we see it every day while it gives color to our daily life and makes our day -to -day life possible. Everyone knows it, we are part of us, it provides the energy that allows our planet to life, however, most people do not know what it is.
The paragraph cited above is proof of this, a book that for some has all the responses of the universe describes it in such a vague and imprecise way that the indication that this lack of precision by the Word of God is due to the fact thatnor they own a true explanation. Unfortunately, for many people this is a topic of complete ignorance, a knowledge of light is in the gloom of knowledge. Due to the previous points I have decided my essay to dedicate to the reader to illuminate the path to the understanding of light (as much as possible to a poor student of the first semester of physics).
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