refraction question

[theonlytycrane]

The correct answer given is (B). I'm trying to understand the setup for this question- A person viewing light rays from an object at an angle in air vs. viewing light rays from an object at the same angle in water?

The difference being the index of refraction from air or from water results in different bending of light assuming a person views both objects at the same distance and angle?

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[aldol16]

This is weird because for the answer to be correct, it must assume that a divide separates the object and viewer, i.e. observer in air and watching the object in water or vice versa.

 

[theonlytycrane]

@aldol16 I should have included this- but I think the question is interpreting the medium change to be between the air and the eye or water and the eye. I wasn't sure if this was a standard interpretation for a problem like this.

 

[aldol16]

Ah, I see. It was an oversight on my part. That would make more sense.

 

[NextStepTutor_2]

@aldol16 I should have included this- but I think the question is interpreting the medium change to be between the air and the eye or water and the eye. I wasn't sure if this was a standard interpretation for a problem like this.

@theonlytycrane

This is a classic Q setup I have seen the AAMC use many times. They are asking you to simply explain the visual difference when looking at an object a given distance away in air, vs. in water. The cause is the bending of light that interacts with the coin in water vs. air that our eyes interpret. Whether you submerge the eye in water or not, the difference in visual perception is that our eyes were designed to focus in air, and when viewing though a material with a different index of refraction, we will get a distorted image.

Another way to test this concept is to throw a coin in a pool, and compare where the coin will "appear" to be to you eyes when the pool is full vs. empty. The coin will appear in a different location to you (farther or closer? ) when the pool is full.

This is why they always tell scuba divers to aim for the bottom of the boat when coming back to the surface, this way you can be sure to come up close to the boat but not actually underneath it (due to the bending of light in water).

Hope this helps, good luck!

 

[BerkReviewTeach]

The correct answer given is (B). I'm trying to understand the setup for this question- A person viewing light rays from an object at an angle in air vs. viewing light rays from an object at the same angle in water?

The difference being the index of refraction from air or from water results in different bending of light assuming a person views both objects at the same distance and angle?

The point of this question has to do with the relative indexes of refraction of air compared to the eye versus water compared to the eye. When light travels from air to our eye, the new n-value is much larger, so the light bends a lot. This allows the light to focus just a hair before our retina and form an inverted, real image on our retina. Our eyes are 'designed' for processing light coming from air so that it converges just before our retina.

Underwater, if you open your eyes, everything seems blurry. This is because light traveling from water into our eye experiences a much smaller change in n-value, so it does not bend as much. The result is that the rays will converge at a point well beyond the retina, resulting in an unfocused image at our retina. Our lens is not designed to contract enough to reduce the focal point to our retina when the light comes from water into our eyes.