Optic properties 

Juan Diego Figueroa

Materials acts different when we expose them to the radiation of light. In order to understand it we should go to the optic properties. These describe the behavior of materials when they are exposed to some kind of electromagnetic radiation. Because of this we can describe the energy of a photon as E=hf, where E is the energy of the photon, h is the Planck constant and f is the frequency. But how f is equal to f=c/ℷ here c is the light speed and ℷ is the wave length thanks to this we get that E=h c/ℷ. With these basic relations we could describe four basic properties for the interaction of material with light rays. These four properties are transmittance, reflection, absorption, and refraction. The transmittance is a phenomenon described by an incident light bean interacting with the surface of a material that crosses the material and then goes out from it. Specifically the ray that goes out is called the transmittance.  The reflection is the light ray that is returns to the same medium that was traveling without goes through the material. One characteristic of this ray is that is emitted from the surface at the same angle of the incident light ray with respect to a perpendicular line to the surface.  The absorption makes reference to the intensity with who the material remains or takes off from the light bean.  Also we have  the refraction is a phenomenon that has been study since 1600 when Willebrord Snel Van Royen discover it, now days we know it as the Snell Law of refraction. The mathematical model is v_1/V_2 =n_2/n_1 =sin⁡〖∅_1 〗/sin⁡〖∅_2 〗  where v1 and v2 represent the velocities of the light in his respective medium; n1 and n2 are the indexes of refraction for medium one and two and φ1 is the incident angle and φ2 is the refracting angle. This refraction is because the speed of the light is different in every medium, and as a medium we can infer some material.  

When a radiation of light interacts with atoms can happen two things, first is called as electric polarization. Electric polarization is the creation of electric dipoles by the separation if charges or the distortion of the nucleus. The other is electronic transitions, it makes reference to when an electron absorb energy from a photon and excite himself to a higher level of energy. From this we can also see reflected the Energy conservation Law, none energy disappear or is destroyed and also a model describe that very well I_0=I_T+I_A+I_R where I0 is the total intensity that carries the ray or the incident intensity and it divided in IT witch is the transmittance intensity, IA the absorbed intensity and IR is the reflected intensity. Why the intensity is related with the energy? This is a question that you may ask so here is the answer intensity is proportional to the power and inverse proportional to the area I=Power/Area and as well P=dE/dt where E represents the energy.