reflectionvisible-light
The problem says:
The certain film on the glass reflects blue light of wavelength 480nm, but does not reflect any red light of wavelength 640nm.
1) If we say that it reflects blue light but no red light, does it mean that we actually see blue light only?
2) As I understand, if something reflects a blue light that automatically means that red light and all other light is absorbed. Is that right?
Thank you.
A truly transparent object doesn't reflect any color in the sense that you seem to mean. How we normally "see" transparent objects is by the refraction of light that they cause and the effect on the image of what lies "behind" them. There is, however, a phenomenon called "total internal reflection" where a transparent object can reflect ALL light that approaches its boundary within a certain range of angles. This is what causes the strange reflection you see when looking up from under water near the surface and how fiber optic systems work.
The amount of reflected light is predicted by Fresnel's equations. The equations are a little cumbersome, but they tell you that the fraction of light reflected depends on the index of refraction of the two materials, as well as the angle of incidence.
One thing though, is since the index of refraction changes with the wavelength of light, then the amount of reflected light also changes with the wavelength!
Realistically though, the index of refraction barely changes at all over the visible spectrum.
In this image, the orange band is the visible spectrum. Those materials labeled "crown" are different types of glass. The range of the index of refraction for these glasses is only about 0.02 or 0.03 over the visible spectrum.
In other words, the glass barely notices the different colours. It reflects all visible light almost identically.
Best Answer
It depends which side of the glass you are observing from.
If you're on the same side as the source, you'll see the reflected blue light.
If you're on the other side, you'll see the transmitted red light.
No. For example, consider your bathroom mirror. It reflect blue light, and it also reflects red light.
Another possibility is it could reflect blue light and transmit (rather than absorbing) red light.