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# can you help me what is deviation of a equilateral triangular prism of 5 cm taking 35 degrees as the ray?

please very important for my praticals

### 1 Answer

- MaXLv 51 decade agoFavorite Answer
To solve this you must know the index of refraction, n.

If the prism use crown glass, n ≈ 1.52

If the prism use SF10 Crystal, n = 1.72803

α = 90° - 35° = 55°

A = 60°

Angle deviation,

ε = α - A + arcsin[sin(A) * sqrt[n^2-(sin(α))^2] - cos(A)*sin(α)]

If n = 1.52,

ε = [55 - 60 + (180/pi) * (arcsin( sin(60*pi/180) * (1.52^2 - ( sin(55*pi/180) )^2 )^0.5 - cos(60*pi/180) * sin(55*pi/180) ))]°

ε ≈ 39.369°

If n = 1.72803,

ε = [55 - 60 + (180/pi) * (arcsin( sin(60*pi/180) * (1.72803^2 - ( sin(55*pi/180) )^2 )^0.5 - cos(60*pi/180) * sin(55*pi/180) ))]°

ε ≈ 60.246°

For more info, go to source...

Source(s): http://ioannis.virtualcomposer2000.com/spectroscop... http://en.wikipedia.org/wiki/BK7_glass http://www.phy.ntnu.edu.tw/oldjava/optics/prism_e....