Page 47 - WAVES

A bat can navigate in darkness

• When ultrasonic waves emitted by the bat hit an
object, they are reflected back and received by the

bat.
• The time between the emission of the sound

waves and reception of the reflected waves
enables the bat to estimate the position of the
object accurately.

• This enables the bat to adjust its direction to avoid
knocking at the object.

Human echolocation lets blind man 'see‘!!!

Exercise 6.6

1. An ultrasonic wave is used to determine the depth of a seabed. A pulse of ultrasound is
generated and travels to the seabed and reflected by it. The time taken by a pulse of ultrasonic
-1
wave to travel to and fro the seabed is 0.28 s. It the speed of sound in the water is 1 500 ms ,
calculate the depth of the seabed.

210 m

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