A speed radar is a device used to measure the speed of moving objects, typically vehicles. It works by emitting radio waves that bounce off the moving object and return to the radar. The device calculates the speed based on the change in frequency of the returned waves, a principle known as the Doppler effect. Speed radars are commonly used by law enforcement to monitor traffic speeds and enforce speed limits. These devices can be stationary or portable, allowing them to be set up in various locations. Some speed radars are equipped with cameras to capture images of speeding vehicles, while others may display the speed to drivers in real-time. They play a crucial role in promoting road safety and reducing accidents caused by speeding.