no critical angle for light from fast /less dense medium to slow/more dense medium?

Question

Why does no critical angle exist for light traveling from a fast (less dense) medium into a slow (more dense) medium?

Answer 1

Well for a given light ray passing between media the follow relationship is true:

n(1)sin(x) = n(2)sin(y) where n(1) is the refraction index of the first medium (the one you're leaving) and n(2) is the refraction index of the second medium (the one you're entering) and x and y being the angle between the light ray and the normal in the first and second medium respectively. The critical angle is defined as the angle at which incoming light may not go from one medium to another. In practice with this equation that means when the sin(y) is equal to or greater than 1 the light will be totally internally reflected.

But the refraction index is just the speed of light in vacuum divided by the speed of light in the medium, n = c/v. So the refraction index in the slower medium will be greater than in the faster medium by this definition. In that case:

n(1)sin(x) = n(2)sin(y) where n(1) < n(2)

If you were to solve for sin(y) you would get the experssion

sin(y) = n(1)/n(2) * sin(x)

Since the light had to enter at a plausible angle (and thus a plausible value of sin(x)) you know that any smaller value of sin(y) will also be plausible. And you know for certain that sin(y) must be smaller because n(1) is smaller than n(2) by definition.

Answer 2

sure, that's because of the fact gentle travels slower in a denser medium. the value of a wave is desperate by using the properties of the medium during which that's travelling. consequently, if a wave enters a sparkling medium its velocity, wavelength and direction all replace. The frequency of the wave maintains to be consistent. This phenomena is regularly occurring as refraction, or the bending of a wave whilst it enters a sparkling medium. If the waves in question are electromagnetic waves, then the ratio of the value of light, c, to the value interior the recent medium, vr, is talked approximately as the Index of Refraction, n. n=c/vr the better the index of refraction the greater gentle is bent. a proper vacuum has an index of refraction of precisely a million, diamonds have an index of refraction of two.40 two. the attitude of occurrence is on the subject remember of the attitude of refraction by using Snell's regulation: n1(perspective of incident)= n2(perspective of refraction)

Answer 3

It has to do with the changes of angle as it tries to transition the boundary. Perfect reflection is not reached in the fast to slow.