MediumPhysicsHigh School (9–10)GeneralWaves & Sound › Wave MotionWaves & Sound › Sound Waves and HearingNumericalBoard Exam
A child hears frequencies from 20 Hz to 20 000 Hz; an older person only up to 12 000 Hz…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A child hears frequencies from to ; an older person only up to . Find the wavelengths in air at , at and at . (Speed of sound )
Need a reminder? The key ideaShow
Loudness depends on the amplitude, pitch on the frequency, and quality on the mixture of frequencies. People hear about to : below is infrasound, above is ultrasound.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. : .
Step 2. : , about .
Step 3. : , that is .
Answer: from down to ; an older person misses the waves shorter than about .
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