Total Internal reflection is Glass Prism Question

In summary, total internal reflection occurs when light is traveling from a more dense medium to a less dense medium, and the angle of incidence is large enough for no refraction to occur. This can be seen in the example of a Glass Isoceles Right Angle Prism, where light travels from glass to air, resulting in total internal reflection. Sources for further understanding of this concept can be found in physics textbooks or online resources.
  • #1
Mohd95
4
0
Question about Total Internal Reflection?
My textbook says that for total internal reflection to occur 2 conditions need to be met. Light is traveling more slowly in the first medium than the second medium and no.2 is the angle of incidence must be large enough for no refraction to occur.

My question is about the first condition why does total internal reflection occur when a light ray is shined through a Glass Isoceles Right Angle Prism like the one in old submarine periscopes. I mean isn't light traveling from air to glass therefore entering from a less dense medium into a more dense medium meaning light is faster in the first medium than the second medium. I don't understand it

I need a good answer please and I am in Grade 10 so don't make it very complex

Heres the link of the prism I am alking about: http://www.gcse.com/waves/images/periscope.gif

Also Sources would be appreciated. Thank You very much
 
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  • #2
The first condition is backwards- total internal reflection can occur when light travels from a more dense to a less dense medium (e.g. glass to air, or water to air), and 'density' refers to the index of refraction: a more dense medium has a higher index.

Does this help?
 
  • #3
Tyvm it definately helpe
 
  • #4
Mohd95 said:
My textbook says that for total internal reflection to occur 2 conditions need to be met. Light is traveling more slowly in the first medium than the second medium
Sounds right to me.
I mean isn't light traveling from air to glass therefore entering from a less dense medium into a more dense medium meaning light is faster in the first medium than the second medium.
Sure, light travels from air to glass, but that's not where the total internal reflection is taking place. The total internal reflection takes place where the light is going from glass to air (or trying to, at least). (Just as Andy Resnick explained.)

I think you just misinterpreted your textbook a bit. In your example, the 'first medium' would be the glass, not the air. (I hope the text went on to explain things a bit more clearly.)
 
  • #5


Total internal reflection occurs when a light ray encounters a boundary between two different mediums, such as air and glass, at a certain angle. This angle, known as the critical angle, is determined by the refractive indices of the two mediums. When the angle of incidence is larger than the critical angle, the light ray is completely reflected back into the first medium instead of being refracted into the second medium.

In the case of a glass prism, the first medium is air and the second medium is glass. The refractive index of air is lower than that of glass, meaning that light travels faster in air than in glass. This is why, as you mentioned, light is traveling from a less dense medium (air) to a more dense medium (glass).

However, when light enters the glass prism at a certain angle, it reaches the boundary between the air and glass at a shallow angle. This means that the angle of incidence is large enough for total internal reflection to occur. In other words, the light ray is hitting the boundary at a steep enough angle that it cannot continue into the glass and is instead reflected back into the air.

In the case of a submarine periscope, the shape of the prism allows for the light to enter and exit the prism at shallow angles, causing total internal reflection to occur. This allows the periscope to function as a mirror, reflecting the image from outside the submarine into the periscope for the viewer to see.

In terms of sources, you can refer to any basic physics textbook or online resources on optics and total internal reflection for more information. I hope this explanation helps clarify your understanding.
 

1. What is total internal reflection in a glass prism?

Total internal reflection occurs when light traveling through a denser medium, such as glass, reaches a boundary with a less dense medium, such as air, at an angle greater than the critical angle. This causes the light to reflect back into the denser medium, rather than refracting into the less dense medium.

2. How does a glass prism create total internal reflection?

A glass prism is a triangular shaped piece of glass with two parallel sides and one angled side. When light enters the prism at an angle greater than the critical angle, it reflects off the angled side and is refracted towards the parallel sides. If the angle of incidence is large enough, the light will be reflected back into the prism due to total internal reflection.

3. What is the critical angle for total internal reflection in a glass prism?

The critical angle for total internal reflection in a glass prism is approximately 42 degrees. This means that if the angle of incidence is greater than 42 degrees, the light will be reflected back into the prism rather than refracted out of it.

4. What is the significance of total internal reflection in glass prisms?

Total internal reflection in glass prisms is essential for many optical devices, such as binoculars, cameras, and telescopes. It allows for the manipulation and redirection of light, making it possible to create images and magnify objects.

5. Can total internal reflection only occur in glass prisms?

No, total internal reflection can occur in any situation where light travels from a denser medium to a less dense medium at an angle greater than the critical angle. This can happen in various materials, such as water, diamonds, and fiber optics.

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