How is sound defined?
AA disturbance of matter travelling outward
BA flow of charged particles through air
CA stream of light released by a source
DA steady pressure applied to a surface
Answer & Solution
Correct answer: A. A disturbance of matter travelling outward
1. Sound is a wave, and a wave is a travelling disturbance.
2. Sound is defined as a disturbance of matter transmitted outward from its source.
3. Because it is a disturbance of matter, sound needs a medium and cannot cross a vacuum.
4. Light needs no medium, which is what separates it from sound.
_Source: OpenStax Physics (high school, CC BY 4.0), Ch 14 "Sound", section Properties of Sound Waves_
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