Apparent depth of an object underwater

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Homework Help Overview

The discussion revolves around determining the apparent depth of an object submerged underwater, utilizing Snell's law and considerations of light refraction. The problem involves understanding the geometry of light paths as they transition from water to air.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to apply Snell's law but expresses uncertainty about finding the angles and the exit point of light from the water's surface. Some participants suggest finding the angles as functions of the distance from a reference point.

Discussion Status

Participants are exploring various interpretations of the problem, with some providing numerical approximations for the distance and apparent depth. There is no explicit consensus, but some guidance has been offered regarding the setup of the problem.

Contextual Notes

The original poster notes a lack of information regarding the exact point along the water's surface where the light exits, which complicates the application of Snell's law. This missing detail is a point of contention in the discussion.

lorenz0
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Homework Statement
A person (the arrow at the upper left of the figure) of height ##h=1.7m## is standing at the edge of a pool of water of depth ##d=1.8m## in which there is an object located at the farthest end of the pool (black ball in the figure). What is the apparent depth of this object for the person looking at the pool, i.e. what is the depth of the object observed by the person (red ball in the figure)?
Relevant Equations
##n_1 \sin(\theta_1)=n_2\sin(\theta_2)##
I would know how to solve this problem if the person had been standing pratically above of the object underwater by using Snell's law and the approximation ##\sin(\theta)\approx\tan(\theta)## fopr ##\theta## small, but in this case I don't see how to find the angles ##\theta_1## and ##\theta_2## and, above all, at what point along the surface of the water the light with come out in such a way as to reach the eye of the person. Without this last information, when I try to set up Snell's law I get (with ##x## representing the distance from the left corner at which the light comes out): ## \frac{d^2+(L-x)^2}{d'^2+(L-x)^2}=1.33^2 ## but I have too many variables.

So, I would appreciate if someone could point me twoards a viable strategy to solve this problem. Thanks
 

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Find the two angles as functions of x.
 
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Likes   Reactions: lorenz0
haruspex said:
Find the two angles as functions of x.
Thanks. I got ##x\approx 18\ m## and an apparent depth of ##d'\approx 0.19\ m##.
 
lorenz0 said:
Thanks. I got ##x\approx 18\ m## and an apparent depth of ##d'\approx 0.19\ m##.
That looks right.
 

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