Why is refraction absent on curved surfaces?

  • Thread starter lalota
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In summary, the curved surface of the glass prevented the light from refracting, and therefore there was no reflection.
  • #1
lalota
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Light is being a sticky unit for me, can anyone help with the following question: "Why is there no refraction at the curved surfaces?"

I've tried reseraching it, but instead I find equations of how it IS possible. Erm.. not quite answering the question. Any help appreciated, thanks!
 
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  • #2
Can you tell us the exact question that was asked? Curved surfaces of what? What was the context?

As you no doubt have discovered, light most definitely does refract at curved surfaces between two different media. That's how lenses work!
 
  • #3
Well, we were conducting an investigation where we would shine a ray of light through a thick, half-circle shaped glass lying flat on a paper, and we measured the angles at which the ray refracted or reflected. When we shone the light at the straight edge of the glass, the rays refracted fine. But when we shone the light through the curved edge, there was always a total internal reflection. Then we were asked to explain why this happens.
 
  • #4
please! -any- help would be appreciated. if I'm still not understood, i can clarify what I'm asking!
 
  • #5
Well, when the ray hits the first surface of the medium, it is refracted (bent). This you seem to have a handle on. When it is refracted, now it is traveling through the medium at a different angle than when it entered.
This new angle, in your situation, when combined with the angle of the curved surface, is either equal to or greater than the "critical angle" needed for internal reflection. The critical angle is simply the angle at which no light will escape the medium. This critical angle is the angle measured between the approaching ray and the normal to the surface.

theta critical = arcsin(n2/n1) where n1 > n2.

That is how to calculate the critical angle for the medium.
Where n1 and n2 are the index of refractions of the two mediums.

I hope this helps. Try calculating it, and seeing if it makes sense. I don't know if you have a copy of the traced rays so that you can measure the angle. Hopefully you have the index of refraction of the glass (or whatever the material was that you were passing the ray through) and the i of r of air is simply 1.
 
  • #6
Thank you so much, Paul! I completely didn't think of using critical angles to explain it! Here's the answer I came up with, I would like to know if it makes sense:

"Once the light entered the glass, it was in the denser medium. In order for refraction to occur, the incidence rays must be less than the critical angle. Yet every time the light approached the glass-air boundary, it was approaching at angles greater than the critical angle. The two conditions necessary for total internal reflection were met (the light is traveling from a more dense to less dense medium, and the angle of incidence is greater than the so-called critical angle), thus all of the incident light at the curved boundary stayed internal and underwent reflection rather than refracting."

And then I included calculations for the critical angle. Any good?
 
  • #7
Sounds good to me. Glad that you got it now. Good luck.
 

1. What is light and how does it travel?

Light is a form of electromagnetic radiation that can be seen by the human eye. It travels in a straight line at a constant speed of 299,792,458 meters per second in a vacuum.

2. What is refraction and how does it occur?

Refraction is the bending of light as it passes through a medium with a different density. This occurs because light travels at different speeds in different mediums, causing it to change direction.

3. How does the angle of incidence affect refraction?

The angle of incidence, or the angle at which light enters a medium, determines the amount of refraction that occurs. The greater the angle of incidence, the greater the amount of refraction.

4. What is the difference between reflection and refraction?

Reflection is when light bounces off a surface at the same angle at which it hits the surface. Refraction, on the other hand, is when light passes through a surface and changes direction due to a change in medium.

5. How is refraction used in everyday life?

Refraction is used in a variety of everyday applications, such as eyeglasses, cameras, and microscopes. It is also used in the production of lenses, prisms, and other optical instruments. Additionally, refraction plays a crucial role in the science of meteorology, as it affects the bending of light in the atmosphere and influences the formation of rainbows.

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