An Arduino Sonar System

Summary: In this project, we will combine an ultrasonic distance sensor with a servo with a little processing code to make a small, desktop sonar sensor to map objects around us. There are a number of similar projects like this posted online, but most of the ones I have tried do not work out of the box. This one will. Overview There are five parts to this project: Evaluating the sonar sensor Evaluating the servo…

A spectacular double rainbow

I first learned about the physics of rainbows in 8.03, sophomore physics, which I took from Walter Lewin. I have never looked at rainbows the same way since. You can watch Prof Lewin’s complete 8.03 lectures on YouTube here. Rainbows are based on dispersion, that the speed of light in water depends on its frequency or wavelength. Dispersion and internal reflection contribute to the very specific set of conditions to see a rainbow. The ray…