How does light bend if it is going from an object with a higher density through an object with a lower density?

1 Answer
Truong-Son N.
Jan 3, 2017

Snell's law relates the indices of refraction for two media with their angles of refraction with respect to the normal, and states:

#n_1sintheta_1 = n_2sintheta_2#

where:

  • #n_i# is the index of refraction of medium #i#.
  • #theta_i# is the angle of refraction (with respect to the normal of the boundary line) in medium #i#.

A denser medium has a higher index of refraction.

Let #n_2 < n_1#, so that we go from a higher-density medium to a lower-density medium. Then, since #n_i prop 1/sintheta_i#, or #n_i prop sintheta_j# (#i ne j#), we must have that #sintheta_2 > sintheta_1#.

Therefore, #color(blue)(theta_2 > theta_1)#, and light bends farther away from the line normal to the boundary between the two media, as shown by the reverse of the light ray below:

http://ww2010.atmos.uiuc.edu/

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