system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we use total internal reflection for fibre optics instead of just ordinary reflection?

I'm a teacher and I gor stumped by this today, couldn't find any answers with Google.
gpt
At ordinary reflection angles, there is both transmission of light and reflection of light at the surface between the two types of material.

At total internal reflection angles, there is no transmission of light, only reflection.

This is important for optical fibers because ordinary reflection will mean light is lost when it transmits through the fiber rather than remain reflected within the fiber. Since optical fibers can span thousands of miles, any little bit of loss per reflection will greatly reduce your optical signal over a distance.

With total internal reflection, you don't get losses from transmission. Interesting enough, if you bend an optical fiber too much, the light going through it doesn't reflect at the internal reflection angle. If the light is visible, you can actually see it transmitting through the bend in the fiber. Optical fibers cannot do the sharp bends possible with metal electric wires.