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Waves

Ultrasound - Range and Direction Finding.

A boat on the sea can send a beam of ultrasound down to the sea floor
where it is reflected back upwards to a detector on the boat.
If both the speed of sound in the water
and the time taken for the ultrasound echo to get back to the boat are known,
then the depth of the sea water at that place can be calculated
since  distance = speed x time.

Ultrasound can be used by fishing boats to find fish
since a shoal of fish between the boat and the sea floor
will return the echo more quickly.

Bats use ultrasound echoes
to build up an image of their environment in darkness.
They can locate insects for food in the air
and know their speed and direction by analyzing the reflected sound.

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Copyright © 2008 Dr. Colin France. All Rights Reserved.