Is the Book Wrong About Total Internal Reflection and Snell's Law?

In summary, according to Snell's law of refraction, the angle of refraction becomes larger as the angle of incidence increases. If n1>n2, then (theta)1<(theta)2. If n1<n2, then (theta)1>(theta)2. Additionally, the frequency of light does not change when it passes from one medium to another.
  • #1
AznBoi
471
0
As the angle of incidence increases, the angle of refraction becomes larger.

Should the underlined word be decreases? why? I think I've found a mistake in the book because according to snell's law of refraction n1sin(theta)1=n2 sin(theta)2 right? If n1>n2 then (theta)1<(theta)2

Wait, I don't know now. I think I'm getting mixed up with angles and indices. =[ Help please.
 
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  • #2
Is there any easy way to remember the relation of n=c/v, snails law, and how the refracted angle behaves when n1>n2 or vice versa?
 
  • #3
Also, how come the frequency of light doesn't change as is passes from one medium to another? How do you know if the speed of the wave, frequency, or wavelength changes? I know that the speed of sound/light changes when it goes through another medium but how do you know if frequency or wavelength change or stays constant? Is there a rule for this concept? Thanks
 
  • #4
bump. help anyone please?
 
  • #5
AznBoi said:
As the angle of incidence increases, the angle of refraction becomes larger.

Should the underlined word be decreases? why? I think I've found a mistake in the book because according to snell's law of refraction n1sin(theta)1=n2 sin(theta)2 right? If n1>n2 then (theta)1<(theta)2

Wait, I don't know now. I think I'm getting mixed up with angles and indices. =[ Help please.


The book is correct. The angle of the refracted ray will bend away from the normal for increasing values of incident angle, in both cases of n1>n2 and n1<n2. Perhaps work out a table of values to see for yourself.
 
  • #6
I will try to explain this, as I learned it. Maybe someone can fill it in a bit.
If you think of the wave fronts being parallel to the boundary between the two media, the number of wave fronts (so frequency) passing a point in medium 1 must be the same as the number of wave fronts passing a point in medium 2. If this were not true, wave fronts would be piling up or being destroyed or whatever and there is no physical mechanism for that to happen. So since the speed changes, the wavelength must change, to keep the relation of velocity = frequency*wavelength valid (in both media).

Hopefully that helps a bit.
 

Related to Is the Book Wrong About Total Internal Reflection and Snell's Law?

1. What is total internal reflection?

Total internal reflection is a phenomenon that occurs when a ray of light traveling through a denser medium reaches the boundary of a less dense medium at an angle greater than the critical angle, causing the light to reflect back into the denser medium instead of refracting into the less dense medium.

2. What is the critical angle?

The critical angle is the angle of incidence at which the refracted ray of light passing through a boundary between two mediums is bent to an angle of 90 degrees. This is the maximum angle at which total internal reflection can occur.

3. What causes total internal reflection?

Total internal reflection occurs due to the difference in the refractive indices of two mediums. When light travels from a medium with a higher refractive index to a medium with a lower refractive index, the light bends away from the normal. If the angle of incidence is large enough, the refracted ray will be bent to 90 degrees, resulting in total internal reflection.

4. What are some practical applications of total internal reflection?

Total internal reflection is used in various devices such as optical fibers, fiber optic communication systems, and prisms. It is also used in devices like endoscopes, binoculars, and periscopes to redirect light and allow for viewing objects from different angles.

5. How does the phenomenon of total internal reflection impact our daily lives?

Total internal reflection plays a crucial role in our daily lives, from powering the internet through fiber optic cables to allowing us to see images through microscopes and telescopes. It also helps in the functioning of devices such as cameras, headlights, and traffic signals. Additionally, total internal reflection is used in medical procedures such as endoscopies and laser surgeries.

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