10.8

Question 1

Vibrations

Answer 1

repeated fast, back-and-forth movements.

Question 2

Compression

Answer 2

the process of pushing a material into itself.

Question 3

Rarefactions

Answer 3

change in the speed of light as it passes from one substance into another. It usually involves a change in direction.

Question 4

Sound Waves

Answer 4

vibrations of particles in the air.

Question 5

Frequency

Answer 5

number of vibrations in one second, or the number of wavelengths passing in one second.

Question 6

Hertz

Answer 6

unit of frequency; its abbreviation is Hz. One hertz is equal to one vibration every second.

Question 7

Pitch

Answer 7

the highness or lowness of a sound. The pitch that you hear depends on the frequency of the vibrating air.

Question 8

Wavelength

Answer 8

distance between two neighbouring crests or troughs of a wave. This is the distance between two particles vibrating in step.

Question 9

Amplitude

Answer 9

maximum distance that a particle moves away from its undisturbed position.

Question 10

Reverberation

Answer 10

longer-lasting sound caused by repeated reflection from hard surfaces.