How do IR, Sonar, Laser, and Radar sensors detect objects?

• A. Emit a signal which is reflected back from objects
• B. Observe atmospheric changes
• C. Observe changes in light
• D. Observe changes in pressure

Answer: (A)

These sensors work by sending out a signal and listening for its return. Infrared, sonar, laser, and radar all use active sensing: they emit a beam or sound, and then detect the reflection that bounces back from objects. By measuring the time between emission and reception (and sometimes the reflection pattern or strength), you can determine how far away the object is and gain information about its location or shape. Infrared uses reflected IR light, sonar uses echoes of sound waves, laser (often LiDAR) uses a laser pulse, and radar uses reflections of radio waves. The other ideas describe passive changes in the environment, which these sensors don’t rely on. So the best description is emitting a signal which is reflected back from objects.