Why does light decrease with depth?
461903
It happens in the atmosphere too, but to a lesser degree.\n\nWater (even pure water) reflects, refracts, and absorbs light.  As light passes through a body of water, some of the light is reflected back, some of the light is refracted (bent), and some of the light is absorbed (leading to warming of the water).  The more water the light has to pass through, the more of the light that is reflected, refracted, or absorbed.  So the deeper you go, the less light will reach you.\n\nTo simplify, just consider absorbsion.  If a cloumn of water one metre deep absorbs 50% of the light that passes through it, then the light at the top of the column will be 100% and at the bottom only 50%.  Add another column of one metre under the first column and it will absorb 50% of the light that passes through it.  It has 50% of the total light available at the top, so only 25% remains at the bottom.\nAnd so on.
1151404
If the deflection surface has any diffraction or diffusion to it, the light may just be redirected imperfectly. 12kV? Jumpin Gigawatts!
998464
moving from a higher to a lower energy level releases energy, producing light, but;\nit only produces light in the visible light spectrum when it moves down to level n=2.  if it ends up at another energy level, the light released will be infared, ultraviolet, etc... depending on where it ends up.
127080
lower atmoshpere is denser, and partially diffuses the light, so I guess you can say that it travels slower there, but only by a tiny bit, given light's huge speed.
82863
The problem is, the air refracts the light as the sun rises. When you see the sun as it rises, it is still actually below the horizon, and it is just that the layers of air are bending the light down so you can see it. The color that gets bent (refracted) the most is the violet light, then the blue, then the green and so on. That is what is responsible for the green flash (since your eye is not as sensitive to the blue and the violet colors, it sees green first). The red actually arrives last, because of these refraction effects. \n\nThe speed of light difference between red and violet is extremely small in air, so this should not have a large influence in the timing, particularly when the atmosphere is only a few tens of miles thick at most (99% of the atmosphere is in the lowest 30 Km).\n\nAfter thinking about this a minute, I realized that you are asking because the sun looks red when it first comes up. This is NOT because the red gets here first. The blue wavelengths are scattered away from the almost white sunlight by the nitrogen and oxygen in the air, leaving the red color. As the sun rises, it goes through less air, and less blue is scattered away, and the sun becomes orange. As the sun rises even higher in the sky, less blue is removed, so the sun looks yellow.
554404
That's the way film works.   Esesentially, the emulsion on the film that receives the most light reacts the most and turns darker.  That's why you have to print the negative onto paper, which essentially  reverses the process, putting the dark back to light and vice versa.
1110351
It is the speed of light.\n\nDarkness is gone at the speed of light when light approaches it at speed of light... when the light moves away at the speed, darkness appears at same speed.
305424
The pressure would be higher, the temperature would be lower, the light would be less.
804004
Perhaps it is because red light has the least energy of all the colors of the visible spectrum.  It has the longest wavelength, thus the slowest frequency, slower than that of blue or violet, for example.  I don't know for sure if this is the reason the materials are not sensitive to it, though.
1014916
i second the a answer.  the field diameter decreases.  even if you solve this problem by process of elimination b c and d are all ridiculous answers if you give it any thought.  e not correct either, because it would occupy a larger portion since you are "zoomed in" and focusing on a smaller section of the slide or whatever so it would occupy a larger portion of the field.
311578
It IS the amount of atmosphere, but primarily because of the refraction it causes.\n\nThink of it as looking through a rainbow from the side.  As light travels through dense layers of air, it bends, and the different colors in white light emerge.
165109
You are seeing the effect of pressure on the rods of your eye, which are fooled into thinking they see light. It should appear on the opposite side from which you press. It's called "phosphene".
555321
I think they've misunderstood.its not speed you are asking about? Depends on the density of the air. light wont travel as far in foggy or smokey conditions as it will under clear conditions.water and air are basically the same thing, different density. That's why it is dark at the bottom of the ocean. It is too dense to penetrate Under clear conditions the distance light will travel if indefinite as far as we know as long as there is nothing interfering or blocking the source
233278
By the same effect that causes uncurtained windows of a house bathed in sunlight to look darker than the rest of the house. The light goes further inside, so a greater proportion of it is diffused and absorbed internally, and less is reflected back out. The water acts as a light pipe, which you can demonstrate by holding a sheet of thin paper with a wet spot up to the light. The ref. provides a fuller explanation.
672737
Must be the perspective. They should actually look smaller (further away) because of the extra distance the light travels from the muscles to the mirror to your eyes.
38582
I realize I am out of my league as far as physics,, but the image reflects directly back to the source in front of it. For the reflection to appear upside down or vertically mirrored the light would have to be bent.\n\nok looked it up.  It is because of the predicatable behavior of light known as the law of reflection
217437
Not in the same way that light reflects. This is an important topic in X-Ray telescopes. See below!