Rainbow question
Classical Mechanics
Level
1
The photo of this rainbow has been taken at the Montmorency Falls in Canada. Notice that the area inside the rainbow (marked by the blue dot) is much "whiter" than the area outside of it (marked by the red dot).
Why is this?
Because there is a higher density of water droplets in the inside of the rainbow
Because the water droplets outside of the rainbow do not scatter white light to the camera
Because the water droplets in the inside of the rainbow are closer to the surface of the water
This is just an accidental fluctuation, and it could be the other way as well
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1 solution
As seen in the illustration (source: Wikimedia Commons ) the angle between the incident light and scattered light depends on where does the incident light hit the surface of the water droplet. For each color there is a maximum angle (about 42 ∘ for red light, and about 41 ∘ for blue light). All of the colors are scattered at angles less than these, reaching the camera as white light coming from inside of the rainbow.
All real rainbows show this effect to some extent. Fake rainbow photos are easy to recognize because they almost never show it.