Point source of light beneath water.

In summary, the problem asks for the diameter of the circle on the surface of the water through which light emerges from a point source 245.0 cm below. Using the index of refraction of water (1.33), the velocity of light reaching the surface can be found to be 2.3E8m/s. The concept of "total internal reflection" explains why light at extreme angles will not make it out of the water.
  • #1
Beeza
118
0
A point source of light is 245.0 cm below the surface of a body of water. Find the diameter of the circle at the surface through which light emerges from the water.


Can someone give me a push start as to how to approach this problem? I can't figure it out for the life of me.

I know that v=c/n, and using 1.33 at the index of refraction of water, I can find the velocity of the light as it reaches the surface is 2.3E8m/s. The point source will emit light isotropically in all directions, and I have the distance to the surface... but for the life of me I can't find how to relate this to the diameter of the circle it will leave on the surface.
 
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  • #2
Does your text cover "total internal reflection"? That's the reason why light that is angled way out to the side won't make it out of the water...
 
  • #3
Thank You. I am such a bonehead sometimes.
 

1. What causes a point source of light beneath water?

A point source of light beneath water is typically caused by a reflection of sunlight off of a smooth surface, such as the surface of the water or a fish's scales. It can also be caused by bioluminescent organisms or artificial light sources, such as underwater flashlights.

2. How does the depth of the water affect the appearance of a point source of light?

The depth of the water can greatly impact the appearance of a point source of light. The deeper the water, the more the light will be diffused and spread out, making it appear less intense. Additionally, as the light travels through the water, it can be absorbed or scattered by particles, further reducing its intensity.

3. Can point sources of light beneath water be used for scientific research?

Yes, point sources of light beneath water can be used for various scientific research purposes. For example, they can be used to track the movement and behavior of marine animals, measure water clarity and depth, and study the effects of pollution on underwater ecosystems.

4. How can the angle of the light source affect the appearance of a point source of light beneath water?

The angle of the light source can greatly impact the appearance of a point source of light beneath water. For instance, if the light source is directly above the water, the light will appear more focused and intense. However, if the light is at an angle, it may appear more spread out and less intense.

5. Are there any safety concerns when observing point sources of light beneath water?

Yes, there are potential safety concerns when observing point sources of light beneath water. It is important to be aware of your surroundings and avoid shining lights directly into the eyes of fellow divers or marine animals. Additionally, be cautious of any underwater hazards, such as sharp rocks or corals, that may be illuminated by the light source.

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