Problem with light grazing along the liquid surface

In summary, the conversation discusses the phenomenon of light rays grazing along the surface of a liquid-filled cuboidal tank at the critical angle, and how this affects what can be seen by an observer. The principle of reversibility and the concept of light scattering are also mentioned. The conversation concludes by acknowledging that a more comprehensive understanding of this phenomenon would require going beyond the idealized model of ray optics.
  • #1
GAURAV DADWAL
37
1
Let's suppose we have a cuboidal tank filled with liquid of density rho,such that
Critical angle of medium is (Ic) now it's
Clear that light rays from the medium that strike at proper critical angle will
Graze along the surface
Now if someone would be along the path of the rays receiving them into his eyes I'm not able to visualize what he will see as light from many parts will be coming into his eyes at once .does that means he will be seeing many parts of tank together at same place this is confusing .please let me have deeper insight into situation Thanx to all those who will help
 
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  • #2
You have it right, I think. You won't see an image of the bottom of the tank, just the sum of all the light coming from the bottom (and sides) of the tank. You could imagine it as an image squashed down to zero height.

You could try it. Get a shallow box or a dish with a pattern on the bottom. Fill it to the brim (can you get an inverted meniscus?) with water. Put it near the edge of a table, let it settle, and then look at it from above. Then just kneel down until you're looking along the surface. As you do, you'll see the pattern on the bottom squish down to nothing.

Compare what you see when the dish is empty.
 
  • #3
Also i had a problem on applying reversibility principle of light in this case
Like how light rays from different parts of tank are grazing along surface ,the principle of reversibility predicts that light from eye that grazes along surface should also enter the medium of liquid at all points at an angle equal to critical angle of medium
But this seems weird pls correct me if I'm wrong somewhere
 
  • #4
Why is the sky blue? Because light both passes through it and scatters off it. That's really only a plausibility argument for the idea of light scattering in multiple places along the surface, butvthe idea isn't totally absurd.

In fact, ray optics is an idealisation. If you think about what the water-air boundary really is - a collection of molecules jiggling and bouncing around - do you really think light will travel neatly along the continually shifting surface? You're going to have to go far beyond ray optics to get a completely satisfactory description of it.
 

1. What is "light grazing" along the liquid surface?

"Light grazing" refers to the phenomenon of light waves interacting with the surface of a liquid at a low angle, causing the light to reflect and scatter in various directions.

2. What causes the problem with light grazing along the liquid surface?

This problem is caused by a mismatch in the refractive indices of the liquid and the surrounding medium, such as air. This leads to total internal reflection, where the light waves are unable to pass through the liquid surface and instead bounce off at a low angle.

3. How does light grazing affect the appearance of the liquid surface?

Light grazing can result in a shimmering or rippling effect on the surface of the liquid, as the reflected light waves create a constantly changing pattern.

4. Can the problem with light grazing be fixed?

Yes, the problem can be fixed by adding substances to the liquid to adjust its refractive index and reduce the mismatch with the surrounding medium. This can include adding surfactants or other additives to change the surface tension of the liquid.

5. Are there any practical applications for studying light grazing along the liquid surface?

Yes, understanding light grazing can be important in various industries such as photography, cosmetics, and oil and gas. It can also be useful in studying the behavior of light in different mediums and for creating optical devices and products.

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