Analysis of rainbows (Part I)
Rainbows are caused by light that enters a water droplet, bends upon entering, reflects off the back surface, and bends again, symmetrically as it exits. Some of the light simply goes straight through. Some reflects several times, but the beam that undergoes a single reflection inside the drop is the one that creates what we know as a rainbow. This demo allows you to experiment with the single and double reflection beams, which produce the primary and secondary rainbows.