In SONAR, we use—

SONAR, an acronym for Sound Navigation and Ranging, is a technology that primarily utilizes ultrasonic waves for underwater detection and navigation. Ultrasonic waves are sound waves with frequencies exceeding 20,000 Hz, which is above the human hearing threshold. These waves are preferred in SONAR systems because their high frequency and short wavelength provide excellent directivity and allow them to travel long distances in water with minimal spreading. Unlike RADAR, which uses electromagnetic radio waves, SONAR relies on mechanical sound waves that propagate effectively through liquid mediums. Active SONAR systems emit these ultrasonic pulses and measure the time taken for the echo to return after reflecting off an object, thereby determining its distance and position. This principle is similar to the natural echolocation used by bats and dolphins.