What is meant by sound ranging? Give one use of sound ranging.

Name the waves used for sound ranging. State one reason for their use. Why are the waves mentioned by you not audible to us?

State the use of echo in medical field.

The wavelength of waves produced on the surface of water is 20 cm. If the wave velocity is 24 ms^-1, calculate (i) the number of waves produced in one second and (ii) the time in which one wave is produced.