Q65 of 199 Page 208

What are infrasonic waves? Name two animals which can produce ultrasonic waves.

Sound waves of frequencies greater than 20,000 Hz are called ultrasonic waves. Porpoises and bats produce ultrasonic waves.


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64

Write any three applications (or use) of ultrasound.

 65

What are infrasonic waves? Name two animals which produce infrasonic waves.

 65

The audible range of frequencies of an average human ear is from 20 Hz to 20 kHz. Calculate the corresponding wavelengths. (Speed of sound in air is 344 m s-1).

 66

Define the following terms:

(1) Echolocation


(2) Echocardiography, and


(3) Ultrasonography.