I had read a passage somewhere stating that there are three possibilities when light falls on an object. It absorbs some of it, reflects some of it and transmits some (pass through). However, I did not see refraction as a possible fate and was curious if refraction simply fell under transmission as both involve light passing through a medium
[Physics] Is refraction a type of transmission
opticsrefraction
Related Solutions
Very reasonable question. I will try to answer it in an intuitive way.
If you have a scattering medium, photons are reflected in random directions; but when you have a refractive medium, something else happens. The photon is not absorbed and re-emitted: instead, the photon interacts with the electrons in the medium, and since these electrons are somewhat bound to the atoms, a displacement (due to the E field of the photon) results in a restoring force. We can measure the degree of displacement or polarization, and express it in terms of the dielectric constant of the material. If there is a lot of polarization, the dielectric constant is high. And the refractive index can be shown mathematically to scale with the square root of the dielectric constant.
What happens then is that the bound electrons move "behind in phase" with the photon, which results in a phase shift of the EM wave (the original phase of the photon which lost a bit of its amplitude, and a lagging phase of the electron). The photon didn't get destroyed - it got delayed, but maintained its direction.
Now when you have an interface between two materials of different refractive index, and light is incident at an angle to that interface, then a greater phase difference builds up between adjacent beams, which is why light is refracted; but if all the light is traveling through the same medium of constant refractive index, all beams will refract by the same amount and remain parallel.
Which is why you can see through a window.
But if you use ground glass, the surface is no longer flat but has been modified to change the direction - and this results in the image behind the glass becoming fuzzy. The same principle exists in the glass used in many showers (original image from Victoria Elizabeth Barnes's posts on bathroom remodeling:
You can clearly see how the bottom half of the window blurs the image of the trees outside. In the article they call this "pebbled" glass.
Glasses which correct for nearsightedness produce a virtual image nearer to the eye than the actual object:
I'm also nearsighted: with my glasses off, I can only focus about a foot in front of my face. My glasses take objects that are infinitely far away and diverge the light coming from them, so that there are virtual images less than a foot from my face; that's how I'm able to focus on objects through my glasses.
I have also observed that, underwater, I can see all the way across the pool with my swim goggles on. Most swim goggles are bubble-shaped, so we can model the swim goggles as a plano-convex lens:
(source)
The curved surface of the "goggle-lens" is the water-air interface; the flat "surface" is the air-air interface, where there isn't any refraction. Now if you build a plano-convex lens out of glass and use it in the air, it's a converging lens. That's because the speed of light is slower in glass than in air, so the light bends towards the fat part of the lens. However your goggles are acting as a lens made of air and submerged in water. Since the relative indices of refraction are reversed, light moving from the water into the "air lens" is bent away from the fat part of the lens. The goggles, when underwater, therefore act like diverging lenses, which is the way to correct for nearsightedness.
I wonder if people who don't need glasses, or people who are farsighted, find things blurrier underwater with goggles on? Perhaps such a swimmer will comment.
Best Answer
Transmitted light is refracted. How much depends on the angle of incidence and the difference in the indices of refraction in both media.
Therefore, as QuIcKmAtHs has pointed out already, refraction is just a special case of transmission.
To describe the behavior of light on an object even more detailed, we introduce finer distinctions as to what happens with the light: it can be refracted, scattered, attenuated, filtered, diffracted, etc. It's often just useful to group these together into reflection, transmission and absorbtion.