What is the critical angle for light traveling through glass?

In summary, the conversation discusses the relationship between light traveling in vacuum and in a medium, as well as the critical angle for the corresponding medium. It also mentions the refractive index for vacuum and the equation for determining the critical angle. The conversation then provides a solution to the problem and suggests using resources such as Hyperphysics and Google to verify the answer.
  • #1
narendra
3
0
Light takes "t1" seconds to travel a distance "x" cm in vacuum and same light takes "t2" seconds to travel "10x" cm in a medium.The critical angle for the corresponding medium is .. ??
 
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  • #2
narendra said:
Light takes "t1" seconds to travel a distance "x" cm in vacuum and same light takes "t2" seconds to travel "10x" cm in a medium.The critical angle for the corresponding medium is .. ??

This sounds like homework.

What is the definition of critical angle? What do you know about the relationship between the critical angle and the index of refraction? Do you have enough information to try to determine the index of refraction in this case?
 
  • #3
the angle of incidence at which angle of refraction becomes 90 degress is critical angle.(C)
relation is
angle of refraction = 1/sinC
Another thing that i know is refractive index for vacuum is "1"

This is not homework..i am preparing for a competetive exam.
I could not figure out how to solve this problem.
 
  • #4
Even though this is not literally "homework", it is "homework-like", that is, a specific exercise that you want to find the solution for. By our rules, it belongs in the "Homework and Coursework Help" forums."

You've already received some help with this, so I will move this to the appropriate forum instead of deleting it and asking you to re-post it. Please use the homework forums for similar questions in the future.

(Questions for clarifying concepts are OK in the main forums.)
 
  • #5
narendra said:
the angle of incidence at which angle of refraction becomes 90 degress is critical angle.(C)
relation is
angle of refraction = 1/sinC
Another thing that i know is refractive index for vacuum is "1"

This is not homework..i am preparing for a competetive exam.
I could not figure out how to solve this problem.

Index?
It's just Snell's Law with the appropriate angles inserted.
Doesn't that equation give you what you want?
If you are still doubtful, it is almost certainly to be found if you Google "Critical Angle Hyperphysics"
If in doubt, always try Hyperphysics first. It has most of the facts and formulae you are likely to need - but it doesn't do your thinking for you. haha
 
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  • #6
i think i have the Solution

when light travels from denser to rarer medium then,
sin r / sin i = v1 / v2
so from given data,

→sin 90 / sin C = [x/t1]/[10x/t2]
→1/sin C = t2/10t1
→ sin C = 10t1/t2
→ C = arcsin(10t1/t2)

I think this is the right answer,
Please correct me if i am wrong.
 
  • #7
Go for it.
This is a confidence thing, I think.
What numerical answer do you get for glass?
Does it look reasonable? (It's unlikely to be 'a bit right', isn't it? If it looks OK then it is ok)
Google critical angle values. The exercise will do you good. Get used to self checking.
 

1. What is the formula for calculating critical angle?

The formula for calculating critical angle is sin-1(n2/n1), where n1 is the refractive index of the medium through which the light is traveling and n2 is the refractive index of the medium in which the light is being refracted.

2. How does critical angle relate to total internal reflection?

Critical angle is the angle at which light traveling from a more dense medium to a less dense medium will be refracted at a 90 degree angle. This is the angle at which total internal reflection occurs, meaning that all of the light is reflected back into the more dense medium instead of passing through the boundary.

3. Can critical angle be greater than 90 degrees?

No, critical angle cannot be greater than 90 degrees. This is because at 90 degrees, the light is refracted at a 90 degree angle and all of it is reflected back into the more dense medium. Any angle greater than 90 degrees would result in the light passing through the boundary instead of being reflected.

4. How does the refractive index affect the critical angle?

The refractive index of a medium is directly proportional to the critical angle. This means that as the refractive index of the medium through which the light is traveling increases, the critical angle also increases. This is because a higher refractive index means that the light will be refracted more, making it more likely to be reflected back into the more dense medium.

5. What is the significance of the critical angle in everyday life?

The critical angle plays a crucial role in optical devices such as fiber optic cables and prisms. It also explains phenomena like mirages and the sparkling of diamonds. Additionally, understanding the critical angle can help us determine the most efficient angles for light to travel in order to minimize loss of light energy.

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