Question 955Navigation General

The correct answer is D) sound waves travel at a constant speed through water. An electronic depth finder, also known as a sonar or echosounder, operates on the principle of sending sound waves into the water and measuring the time it takes for the sound waves to reflect off the seabed and return to the transducer. By knowing the constant speed of sound in water, the depth can be calculated based on the round-trip time of the sound waves. The other options are incorrect because they do not accurately describe the underlying principle of how an electronic depth finder operates. Pressure increases with depth (A), radar signals travel through air not water (B), and radio signals reflect from the water surface rather than the seabed (C).