sonar

Everyday

1. Sonar is a way of finding things under water by sending out sound waves and listening for their echoes. tree →
2. Sonar is also the machine that does this, used by ships and submarines. tree →
3. Animals such as bats and dolphins use a natural kind of sonar called echolocation. tree →

In the lessons

In science lessons about sound, sonar shows that sound travels through water and bounces back as an echo; the time the echo takes tells the distance. Ships use sonar to measure the depth of the sea, find fish or find wrecks. Phrases: «sonar system», «on sonar», «use sonar».

Examples

• The submarine used sonar to find the shipwreck. tree →
• Fishing boats use sonar to find shoals of fish. tree →
• Bats use a kind of natural sonar to catch moths. tree →
• The sonar screen showed a large shape below the ship. tree →
• Sonar works by sending out sound and listening for the echo. tree →
• Dolphins find food with echolocation, which is like sonar. tree →

Note

Uncountable. It is short for «sound navigation and ranging». In maths problems: the echo goes there and back, so to find the distance, halve the total distance the sound travels (distance = speed × time ÷ 2).