What is the main function of sonar on a submarine or surface ship?

What is the main function of sonar on a submarine or surface ship?

• A. To measure water depth.
• B. To communicate with satellites.
• C. To detect and locate underwater contacts by emitting/receiving acoustic signals.
• D. To map seabed topography.

Answer: (C)

Sonar is used to find and locate underwater objects by emitting sound and listening for its echoes. When a submarine or surface ship sends out a sound pulse (active sonar), it measures how long the echo takes to return to determine range, and analyzes the direction and characteristics of the echo to pinpoint position and movement. This capability to detect and identify underwater contacts—ships, submarines, or other objects—is the core purpose of sonar in maritime operations.

Other options describe related tools or different tasks. Measuring water depth or mapping seabed topography are specific applications that use sonar, but not the general function of locating underwater contacts. Communicating with satellites relies on radio waves, not acoustic signals, so it isn’t what sonar does.