Question
Answers

Ultrasound has a frequency of vibration
A. Between $20$ and $20000Hz$
B. Below $20Hz$
C. Above $20000Hz$
D. Between $500$ and $10000Hz$

Answer
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Hint: In physics, an acoustic wave that propagates through vibrations through a medium such as solid, liquid, or gas is called sound. The reception or perception of these kinds of waves by the brain is called sound according to human physiology. Human ears can perceive up to a particular range of frequency.

Complete step by step answer:
Human ears can receive up to a particular range of sounds. The range of frequency lying between $20Hz$ and $20000Hz$ is perceivable to humans. Sounds that have a frequency greater than $20000Hz$ are called ultrasonic sounds. Some animals can hear ultrasonic sounds. Dogs can hear sounds greater $20000Hz$ than but humans cannot hear such sounds. The frequency range that dogs can hear varies from $67 - 45000Hz$. The frequency that lies between $20000Hz$ and $45000Hz$ can be heard by dogs but not by humans.

Hence, the correct answer is option (C).

Additional Information:
The sounds that have a frequency less than $20Hz$ are called infrasound. This range of sounds is additionally inaudible to humans. The capacity of perception varies in several animal species. For different purposes like predation, detection of danger, communication, navigation, etc. Many animals use sounds. Some animals have special organs to produce sounds. Animals like whales, animals, etc. can detect infrasound and use it for communication. Unwanted sound is called noise.

Note: Ultrasound is employed for several medical and research purposes. Volcanic eruptions can be detected using Infrared sound. Depending on the medium through which it passes the sound the speed of sound changes. The speed of sound will move through solids. The physical properties of sound aren't constant through a medium.