Having trouble finding the angle of deflection of light

In summary, the conversation discussed finding the angle of deflection in a prism and how to prove that it is equal to the formula sin(A+δ)/2 = n*sinA/2. It was determined that the incident and exit angles are the same and that the formula is only valid for minimal deflection. The conversation also mentioned that the teacher made a mistake in labeling the angles, making the problem easier to solve.
  • #1
kliker
104
0
we have this picture

http://img190.imageshack.us/img190/1128/60283381.jpg

how can i find the angle of deflection?

i must show that it is: sin(A+δ)/2 = n*sinA/2
 
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  • #2
You need to apply Snell's Law at the the two interfaces. Note that since the incident angle with respect to the normal is the same as the exit angle with respect to the normal, symmetry demands that the ray travel parallel to the base inside the prism. Assume that the prism angle (at top) is known because the angle of deflection depends on it.
 
  • #3
kuruman said:
You need to apply Snell's Law at the the two interfaces. Note that since the incident angle with respect to the normal is the same as the exit angle with respect to the normal, symmetry demands that the ray travel parallel to the base inside the prism. Assume that the prism angle (at top) is known because the angle of deflection depends on it.

thanks but how can we know if the incident angle with respect to the normal is the same as the exit angle?

it doesn't say anything like that, how can we assume this

also

i applied snell but i have sina/sinb = n and sinc/sind = 1/n

also i have proven that A = b + c

http://img130.imageshack.us/img130/6987/50944329.png

im having trouble finding that sin(A+δ)/2 = n*sinA/2 :(

thank you again
 
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  • #4
As best as I can say from your posted diagram at

http://img190.imageshack.us/img190/1128/60283381.jpg

both incident and exit angles are labeled θa. Is this not true?
 
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  • #5
no I think the second one is θb where b = β(the greek letter)
 
  • #6
if we supposed that it is the same how could we reach the desired solution?
 
  • #7
Referring to your drawing, it is easy to find that the deflection is a+d-A.
The formula you have to prove is valid only for the minimal deflection. The deflection is minimal when the incident and the exit rays are symmetrical: a=d.

ehild
 
  • #8
ok guys i figured everything out

the teacher made a mistake it was θα the second one too, it was easy to solve i thought they were different

thanks everyone
 

FAQ: Having trouble finding the angle of deflection of light

1. What is the angle of deflection of light?

The angle of deflection of light refers to the change in direction of a light ray as it passes through a medium with a different refractive index.

2. Why is it important to find the angle of deflection of light?

Knowing the angle of deflection of light is important in various applications, such as designing optical instruments and understanding the behavior of light in different materials.

3. How is the angle of deflection of light calculated?

The angle of deflection of light can be calculated using Snell's law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equal to the ratio of the refractive indices of the two mediums.

4. What factors can affect the angle of deflection of light?

The angle of deflection of light can be affected by the refractive index of the medium, the angle of incidence, and the wavelength of the light.

5. What techniques can be used to measure the angle of deflection of light?

Some common techniques for measuring the angle of deflection of light include using a protractor and a light source, using a laser beam and a diffraction grating, and using a spectrometer.

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