Angle of Refraction Given Wavelength & Speed of Light in Air & Glass

AI Thread Summary
The discussion revolves around calculating the angle of refraction for light entering glass from air, using Snell's Law. The light has a wavelength of 600 nm in air and travels at 0.650 times the speed of light in air within the glass. The angle of incidence is given as 40°, and the expected angle of refraction is 24.7°. Participants emphasize the importance of ensuring the calculator is set to degrees, as confusion arises from using radians. The main challenge is bridging the gap in understanding how to apply Snell's Law correctly to find the angle of refraction.
Oneablegal
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Homework Statement



Light of wavelength 600 nm in air enters a piece of glass. The speed of light in this glass is 0.650 times the speed in air. Calculate the angle of refraction, Given that the angle of incidence of this light ray is 40°.

Homework Equations


Snell's Law
Sin(θ1)/sin(θ2) = v1/v2


The Attempt at a Solution



I calculated the wavelength to be 390 nm. (600nm x 0.65). I know the Speed of light in glass is less than an air so light is going to slow down and bend towards the normal, therefore the angle of refraction will be less then the incident 40°. I know the practice problem answer is 24.7 degrees. I need help bridging the gap, so to understand this problem. Please help! Thank you in advance.
 
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Hi Oneablegal! :smile:

First … did you set your calculator to degrees (not radians)? :wink:

(If so, please show how far you've got.)
 
tiny-tim said:
Hi Oneablegal! :smile:

First … did you set your calculator to degrees (not radians)? :wink:

(If so, please show how far you've got.)
Hi! Yes, the calculator is set to degrees. This is as far as I have gotten. I have tried to set this up numerous times, with angle 1 set equal to sin(40) or 0.745113. Angle 2 or the angle of refraction is unknown. V1 I have as 1.00 and V2 as 0.65. I am lost from here...

Thanks again!
 
Last edited:
Hi Oneablegal! :smile:

(just got up :zzz:)
Oneablegal said:
Hi! Yes, the calculator is set to degrees.

…with angle 1 set equal to sin(40) or 0.745113

he he! :biggrin:

No it isn't!

sin(40 radians) = 0.745113 :wink:
 
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