- #1
jaumzaum
- 434
- 33
Hello!
Just now I began to question myself about something I learned many years ago.
When we are outside of a pool and see a coin in the floor of the pool (underwater) we think that the coin has an apparent depth that is smaller than the real depth. To calculate this we extrapolate the light ray that reaches our eyes as if it was not refracted and intercept this ray with the vertical line that passes through the coin. The point of interception is where we think the coin is, as in the figure below:
My question is: During this calculation the thing that remained "constant" was the horizontal position of the coin (we assumed that the image of the coin is in the same vertical line, perpendicular to the surface of the water, i.e. line OA). Why is that? I mean, I understand that, due to diffraction, our brain would "think" that the image is in line BI, because that is the direction of the ray that reaches our eyes. But it's not obvious to me why it would also "think" that the image is in the same vertical line as the real object.
Thanks!
Just now I began to question myself about something I learned many years ago.
When we are outside of a pool and see a coin in the floor of the pool (underwater) we think that the coin has an apparent depth that is smaller than the real depth. To calculate this we extrapolate the light ray that reaches our eyes as if it was not refracted and intercept this ray with the vertical line that passes through the coin. The point of interception is where we think the coin is, as in the figure below:
My question is: During this calculation the thing that remained "constant" was the horizontal position of the coin (we assumed that the image of the coin is in the same vertical line, perpendicular to the surface of the water, i.e. line OA). Why is that? I mean, I understand that, due to diffraction, our brain would "think" that the image is in line BI, because that is the direction of the ray that reaches our eyes. But it's not obvious to me why it would also "think" that the image is in the same vertical line as the real object.
Thanks!