When light is transmitted through material what happens?

Question

A) it’s average speed will change compared to transmission through other materials

B) it’s actual speed changes

C) it will become scatted and loose coherence

D) it will gain intensity in proportion to its change in speed

Answer 1

Hi Cathy L.,

The question implies a distinction between transmission through a medium and transmission through a vacuum. So (B). "Average" speed is irrelevant to this question! There was no mention of it being coherent to begin with, so it can't very well lose a quality it didn't have initially. And intensity -- the measure of energy passing per second -- doesn't change unless some of the light is absorbed. Which it wasn't.

So, this question is indirectly engaging your knowledge of "index of refraction". If you think you have that idea well in hand, try this on: the index of refraction is a complex number, not just a real one! This comes into play when calculating some of the interesting things light can do, such as partially reflecting and partially refracting at an interface; that and polarization effects, and also evanescent waves (when light tries to penetrate an interface, but then totally reflects. Such as reflecting from a shiny metal surface. But it has already sampled the material on the other side!)

-- Cheers, --Mr d.