less than 20 Hz
The frequency of subsonic sound is less than 20 Hz
subsonic sound refers to a sound which has a wave that travels slower than the speed of sound.
- frequency of audible sound: 20 Hz to 20,000 Hz
<u>Thus </u>subsonic sound < 20 Hz
Small objects vibrate quickly and produce lots of waves each second, and as the length of the bells are short the wave length become short too,so small bells have a high frequency hence high pitch.
A <u>scanner</u> is a type of communications equipment that functions as a radio receiver and searches across several frequencies.
A scanner is a kind of a radio receiver that has the ability to receive multiple signals.
There are three modes which a scanner uses for acting as a radio receiver. The scan mode of the radio receiver constantly changes frequencies that helps in transmissions. There is also a manual scan mode that allows the users to search for their interested frequencies. The search mode allows the users to search through two sets of frequencies.
A scanner is a type of communication equipment that is easy to use with various features such as the volume, numeric keypad, trunk tracking etc.
To learn more about scanners, click here:
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Answer: I believe that it is A and D. Or A or D.
A, D
Explanation: