Refraction is defined as a surface phenomenon. When a ray of light passes at an angle other than normal to a surface, the phase velocity of the light reduces, if entering a denser medium (higher refractive index), and increases if it moves to a rarer medium. Moreover, the direction of the light wave is changed a bit based on the sine rule (Snell's law). Further explanation of conservation of energy is also outlined by Fresnel's equations, where part of the light is reflected and part refracted.
The above is just a short summary of refraction as we are taught in school. A bit further of explanations are required, to ensure we have covered all aspects. Both medium are considered transparent for these experiments. Translucent materials would absorb part of light and reflect some of the light as well. Moreover, we are considering homogeneous medium for simplicity sake. In heterogeneous / non-uniform medium, there will be more collisions of the photons, absorption, reflection, etc.
The overall concept however does raise some questions at a quantum level. At quantum level, we all are told that there is lot of empty space between the nucleus and electrons. There is lot of empty space between atoms that form a molecule (say glass molecules). There is very higher order of empty space in case of air and we have very highly mobile atoms/molecules. In case of water, even though there is Brownian movement, there is still quite a bit of empty space.
We have usually simplified understanding of refraction into 2-dimensional ray-theories. We are all told of the rays being on the same plane. However, a "surface" / boundary between two medium is usually 3-dimensional. What really happens to the angles of incidence and refraction?
Other than that, we have many more questions.
(a) As the photon approaches the line of boundary between the two mediums what influences the change in direction of light? Are there different kinds of fields in the two mediums? Does Glass or Water have a different field, that affects the path of light (or path of photon)?
(b) Do the atoms/molecules exert any electro-magnetic field affecting the electro-magnetic waves? Is there a regular field that exists around every atom/molecule? If yes, what is its effect - if not, how does the surface, its angle with respect to the approaching photon, etc., cause the consistent effect?
(c) How is the change of direction different for different angles of approach to the surface separating the two mediums? Does the light sense the alignment of the series of atoms/ molecules of the medium? Or is this also a function of "alignment of the field and its effect"?
(d) At what point does the change in direction happen - as soon as it is within X distance of the field near the boundary? What is value of X that we can reasonably surmise, for a significant effect of change in path?
(e) If there is a very thin film of the medium (hence light emerges back into first medium), then how is the change in path perfectly in opposite direction while going through all that empty space between electrons, nucleus, atoms and molecules? A question similar to (c) above, but now the light diverges from normal (assuming the film has higher refractive index).
(f) So, is refractive index a function of this "field" and is the field same as the electromagnetic field? Or is it a function of the electromagnetic field? Or is it possible that the field is something entirely different? When we think of concept of heat, temperature, etc., along with the refraction concept, and then electromagnetic fields - where do they all fit in, in the quantum level?
Too many questions raised when we dig deeper, and still searching for answers.
Maybe a kind reader will point us to some good information that can set right the simple doubts of a common man.
The above is just a short summary of refraction as we are taught in school. A bit further of explanations are required, to ensure we have covered all aspects. Both medium are considered transparent for these experiments. Translucent materials would absorb part of light and reflect some of the light as well. Moreover, we are considering homogeneous medium for simplicity sake. In heterogeneous / non-uniform medium, there will be more collisions of the photons, absorption, reflection, etc.
The overall concept however does raise some questions at a quantum level. At quantum level, we all are told that there is lot of empty space between the nucleus and electrons. There is lot of empty space between atoms that form a molecule (say glass molecules). There is very higher order of empty space in case of air and we have very highly mobile atoms/molecules. In case of water, even though there is Brownian movement, there is still quite a bit of empty space.
We have usually simplified understanding of refraction into 2-dimensional ray-theories. We are all told of the rays being on the same plane. However, a "surface" / boundary between two medium is usually 3-dimensional. What really happens to the angles of incidence and refraction?
Other than that, we have many more questions.
(a) As the photon approaches the line of boundary between the two mediums what influences the change in direction of light? Are there different kinds of fields in the two mediums? Does Glass or Water have a different field, that affects the path of light (or path of photon)?
(b) Do the atoms/molecules exert any electro-magnetic field affecting the electro-magnetic waves? Is there a regular field that exists around every atom/molecule? If yes, what is its effect - if not, how does the surface, its angle with respect to the approaching photon, etc., cause the consistent effect?
(c) How is the change of direction different for different angles of approach to the surface separating the two mediums? Does the light sense the alignment of the series of atoms/ molecules of the medium? Or is this also a function of "alignment of the field and its effect"?
(d) At what point does the change in direction happen - as soon as it is within X distance of the field near the boundary? What is value of X that we can reasonably surmise, for a significant effect of change in path?
(e) If there is a very thin film of the medium (hence light emerges back into first medium), then how is the change in path perfectly in opposite direction while going through all that empty space between electrons, nucleus, atoms and molecules? A question similar to (c) above, but now the light diverges from normal (assuming the film has higher refractive index).
(f) So, is refractive index a function of this "field" and is the field same as the electromagnetic field? Or is it a function of the electromagnetic field? Or is it possible that the field is something entirely different? When we think of concept of heat, temperature, etc., along with the refraction concept, and then electromagnetic fields - where do they all fit in, in the quantum level?
Too many questions raised when we dig deeper, and still searching for answers.
Maybe a kind reader will point us to some good information that can set right the simple doubts of a common man.
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