Why does not a glass block disperses white light whereas a prism does? This is a quest. in my book?

Question

please answer this in a good manner? monday is my physics exam

Answer 1

It does a little if it's big enough. Because the back surface is parallel to the first surface, though, light of all frequencies exits parallel to the line of entry. So the only dispersion you get is the separation of the light within the cube. In a regular prism, the light of different frequencies exits the prism at different angles, so you see a rainbow even if the prism (or water drop) is tiny.

Answer 2

Like Bekki B said. Just to expand a bit, the first surface for either shape bends the different frequencies at different angles. At this stage, the bending and dispersion is the same for both shapes, assuming the incident angle is the same.

On exiting, the second (parallel) surface for the block corrects the different angles back to the original common incident angle. By comparison, the second surface of the prism further magnifies the angle differences.

So the different frequencies stop separating after they exit the block, meaning you need a deep block to get much dispersion. With a prism, the colors continue to separate at an even greater angle after exiting, so you can project a nice split on a white screen.

Answer 3

A prism refracts light. A glass block only diffuses light.

Answer 4

Why does Bekki always get there before me? I want some points!

Answer 5

read ur book