Answer to Question #92283 in Optics for jane montgomery

Question

Explain how a tube of glass in a fiber optic cable can keep a beam of light reflecting inside of it, even though the glass is transparent to the light.

Answer 1

The light does not propagate into the air when the light moves from glass into the air,, and therefore moves inside the glass tube. This is possible if the incidence angle is greater than the critical incidence angle for these two media.