Geometric optics is the part of physics responsible for studying the behavior of light.
Ever since he knows himself as a rational being, man has asked himself this question. Something so intriguing led the ancient Greeks to believe that light came from objects, and that they all emitted light, making it possible to see them.
The responsibility of first studying this phenomenon rested with Isaac Newton. He analyzed the behavior of light through the beams of light ray emitted by a luminous body.
He then arrived at the result that the luminous body was composed of particles that, when leaving it, illuminated the object, making it possible to see it. He explained with this the phenomena referring to luminosity: reflection and refraction.
As soon as Newton presented the results of his experiments, Christian Huygens also presented his theory, saying that light is a wave phenomenon, which was not immediately accepted because of Newton’s prestige.
Subsequently, Huygens’ theory was considered definitive, due to the veracity proven by Fizeau and Foucault.
However, this theory fell apart in 1887, after Hertz discovered the photoelectric effect, in which he observed that an illuminated and electrically charged body gives off negative electrical charges, which was later complemented by Albert Einstein when he considered light as a phenomenon of corpuscular nature, showing the duality of light behavior, currently accepted theory.
We can then define Geometric Optics as the part of physics responsible for studying the behavior of light.