Question

1. Name the waves used for echo depth sounding. 
2. Give one reason for their use for the above purpose.
3. Why are the waves mentioned by you not audible to us?

Answer 1

1. Ultrasonic waves are used for echo depth sounding.
2. They are used because they can travel through water and produce clear echoes after reflection from the seabed.
3. Ultrasonic waves are not audible to humans because their frequency is above 20,000 Hz, which is beyond the human hearing range.