Concept Items

What is the amplitude of a sound wave perceived by the human ear?

1. loudness
2. pitch
3. intensity
4. timbre

The compressibility of air and hydrogen is almost the same. Which factor is the reason that sound travels faster in hydrogen than in air?

1. Hydrogen is more dense than air.
2. Hydrogen is less dense than air.
3. Hydrogen atoms are heavier than air molecules.
4. Hydrogen atoms are lighter than air molecules.

What is the mathematical relationship between intensity, power, and area?

1. $I=\frac{P}{A^2}$
2. $I=PA$
3. $I=\frac{A}{P}$
4. $I=\frac{P}{A}$

How does the "decibel" get its name?

1. The meaning of deci is “hundred” and the number of decibels is one-hundredth of the logarithm to base 10 of the ratio of two sound intensities.
2. The meaning of deci is "ten" and the number of decibels is one-tenth of the logarithm to base 10 of the ratio of two sound intensities.
3. The meaning of deci is “one-hundredth” and the number of decibels is hundred times the logarithm to base 10 of the ratio of two sound intensities.
4. The meaning of deci is “one-tenth” and the number of decibels is ten times the logarithm to base 10 of the ratio of two sound intensities.

Two sources of sound producing the same frequency are moving towards you at different speeds. Which one would sound more high-pitched?

1. the one moving slower
2. the one moving faster

When does a yo-yo travel the farthest from the finger?

1. when the amplitude of the finger moving up and down is greater than the amplitude of the yo-yo
2. when the amplitude of the finger moving up and down is less than the amplitude of the yo-yo
3. when the frequency of the finger moving up and down is equal to the resonant frequency of the yo-yo
4. when the frequency of the finger moving up and down is different from the resonant frequency of the yo-yo

What kind of waves form in pipe resonators?

1. damped waves
2. propagating waves
3. high-frequency waves
4. standing waves