How does refraction of light in water affect the perceived location of objects?

In summary, a child standing at the edge of a 1.2m deep pool sees a brick at a horizontal distance of 2.0m from the side of the pool. However, due to refraction, the actual position of the brick is closer to the side of the pool, at the location where the refracted ray hits the surface of the water. The child observes the brick in the extension of the straight line hitting their eye.
  • #1
CAF123
Gold Member
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Hi,
I was trying the following question;
'A child of height 90 cm is standing at the edge of a 1.2m deep swimming pool. She
looks into the water and sees a brick lying on the bottom of the pool. From the
child's perspective, the brick appears to be 2.0m horizontally away from the side
of the pool. In reality, how far away is the brick from the side of the pool? (The
refractive index of water is 1.33. Assume the child's eye level is at 90 cm and the
pool is completely filled with water.)'

I know how to solve the problem, it is just I am having a little difficulty with some of the details. I took it to mean that the actual position of the brick would be the position that would be observed if there was no water, in which case it would be at the location following the straight ray (see diagram). I then took it to mean that the observed position would be at the position of the refracted ray . However, the solution has these the other way round - that is, the actual position at the refracted ray and observed position at the straight ray.( This is shown in the attachment)

Any clarification of why this is would be very helpful,
Thanks.
 

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  • #2
We see an object in the direction from where the light ray emerging from the object arrives. A light ray from the brick (red) refracts somewhere at the surface of water and arrives at the eye of the child. The child observes the brick in the extension (blue) of the straight line hitting his eye.

ehild
 

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  • refraction.JPG
    refraction.JPG
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Related to How does refraction of light in water affect the perceived location of objects?

What is refraction of light in water?

Refraction of light in water is the phenomenon where light bends as it passes from one medium (such as air) into another medium (such as water). This bending of light is caused by the change in speed of light as it travels through the different medium.

What is the cause of refraction in water?

The change in speed of light as it passes through different media causes the refraction of light. This change in speed is due to the difference in the optical density of the two media.

How does the angle of incidence affect the refraction of light in water?

The angle of incidence, which is the angle at which light enters the water, determines the amount of refraction that occurs. As the angle of incidence increases, the amount of refraction also increases.

Why does a straw appear bent when placed in a glass of water?

This is because of the refraction of light in water. The light from the straw is refracted as it enters the water, making it appear as if the straw is bent at the water's surface.

What is the relationship between the refractive index and the speed of light in water?

The refractive index of a medium is directly proportional to the speed of light in that medium. This means that as the refractive index of water increases, the speed of light decreases, resulting in a greater amount of refraction.

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