Total internal reflection (T.I.R.)

In summary: However, for low velocity waves (such as sound) the pressure wave can travel through the medium - as long as the medium does not have a higher velocity than the pressure wave.]
  • #1
skywalker09
38
0
Why is it that T.I.R. only occurs when a light is traveling from a denser to a rarer medium? Intuition suggests that this should happen when going from a rarer to a denser medium. Care to get into some mathematics?

Also, can the interface between 2 media be designed so that there is 100% transmission?

EDIT:

Do pressure waves (sound) also exhibit T.I.R.?
 
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  • #2
skywalker09 said:
Why is it that T.I.R. only occurs when a light is traveling from a denser to a rarer medium? Intuition suggests that this should happen when going from a rarer to a denser medium. Care to get into some mathematics?
Start with Snell's law for refraction.
 
  • #3
What about the physical reason? What is it about the nature of matter and light which causes this?
 
  • #4
skywalker09 said:
Also, can the interface between 2 media be designed so that there is 100% transmission?

Do pressure waves (sound) also exhibit T.I.R.?

Pressure waves also satisfy Snell's law and can have TIR.
A three media interface is needed for 100% transmission.
A "non-reflective" coating is used between the two original media.
 
  • #5
[Sound only manifests as a pressure wave in all of its bulk when it travels through fluids - it also travels as shear waves (in solids). Sound can and does exhibit TIR, although this behaviour is limited to waves which are incident at an angle greater than the "critical angle". The so-called "sound channel" in the oceans is so-named because sound at greater than the critical angle will propagate in this layer, only able to spread its energy cylindrically, the energy travels further so is good for long distance messaging. The basic rule of thumb is that the ray will tend to be "repelled" by higher velocity media, so if you have a high velocity boundary surrounding a low velocity tube the energy will not be able to escape.
 

FAQ: Total internal reflection (T.I.R.)

What is Total Internal Reflection?

Total Internal Reflection (T.I.R.) is a phenomenon that occurs when a ray of light passing through a dense medium reaches the boundary of a less dense medium at an angle greater than the critical angle. Instead of refracting, the light is completely reflected back into the denser medium.

What causes Total Internal Reflection?

Total Internal Reflection is caused by the difference in the refractive indices of two mediums. When light passes from a denser medium to a less dense medium, it slows down and bends or refracts away from the normal line. If the angle of incidence is increased beyond the critical angle, the light cannot pass through and is reflected back into the denser medium.

What is the critical angle?

The critical angle is the angle of incidence at which light passing through a denser medium is refracted at an angle of 90 degrees. At this angle, the refracted ray grazes the boundary and any further increase in the angle of incidence will result in total internal reflection.

What are some real-life applications of Total Internal Reflection?

Total Internal Reflection has many practical applications, including in optical fibers used for telecommunication, endoscopes used in medical procedures, and prism-based binoculars and cameras. It is also used in the design of optical lenses and mirrors in telescopes and microscopes.

What is the difference between Total Internal Reflection and regular reflection?

The main difference between Total Internal Reflection and regular reflection is the angle at which the light is reflected. Regular reflection occurs when light is reflected at an angle less than the critical angle, while Total Internal Reflection occurs at angles greater than the critical angle. Additionally, regular reflection occurs at any interface between two mediums, while Total Internal Reflection only occurs when light passes from a denser medium to a less dense medium.

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