Fizeau experiment

The Fizeau experiment is named after a French physicist named Armand Fizeau. He studied how light travels through water and air. To do this, he used a setup with a light source, a rotating wheel with blades, a mirror, and a detector. When the light from the source hits the rotating wheel with blades, it reflects off the blades and only a very small amount of light goes through each blade. Then the light bounces off the mirror and goes back to the detector. The rotating wheel causes the light to reach the detector at different times depending on how fast it's spinning. By measuring how long it takes the light to go back and forth, the velocity of the light in water or air can be measured.