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Flashcards in Abeka Science Chapter 11 Deck (56):
0

A _________ is a periodic back-and-forth motion, or oscillation, that transmits energy.

wave

1

What is the substance called through which a wave transfers?

The medium (plural media)

2

What are the high points of a wave called?

The crests

3

What are the low points of a wave called?

Troughs

4

What are the two major types of wave?

Transverse waves and longitudinal waves

5

What travels through the spring when a few coils at one end of the spring are squeezed together and released?

A compression pulse

6

What is a series of waves called?

A wave train

7

What follows close behind the compression pulse and consists of a portion of the spring in which the coils are spread out?

Rarefaction pulse

8

What is the length of a single wave?

wavelength

9

What is the maximum distance that particles are displaced by a wave?

Amplitude

10

What is the number of waves that pass a given point per unit time?

Frequency

11

What are vibrations traveling through a medium in the form of longitudinal pressure waves?

Sound

12

What is the SI unit of frequency?

The hertz

13

What is the time needed for a wave to pass?

The wave's period

14

Can one have sound if there is no medium?

No

15

Will the speed of the wave change if the medium does not change?

No, it will be the same.

16

What is speed related to wavelength and frequency?

Directly proportional.

17

What device is used to demonstrate the behavior of waves?

A ripple tank

18

What are the waves that strike an object called?

Incident waves

19

What are waves called that bounce off an object?

Reflected waves

20

What law states that the angle of incidence equals that angle of reflection?

The law of reflection.

21

What is the imaginary line perpendicular to the reflecting surface?

The normal

22

Where do the refracted waves bend?

Always towards the medium that slows them down.

23

What is the spreading out of a wave after it passes through a narrow opening called?

Diffraction

24

True or False:
Diffraction causes the wave to spread out evenly when the opening is roughly equal to one wavelength.

True

25

What is the reinforcement or cancellation that occurs when when two or more waves meet?

Interference

26

What are the two types of wave interference?

Constructive and destructive interference

27

What does a complete sound wave consist of?

A compression pulse- a high pressure area in which the air molecules are bunched together, and a rare fraction pulse- a low pressure are in which the air molecules are farther apart.

28

Who used an alarm in a vacuum to show that sound needs a medium in order to be heard?

Robert Boyle

29

What is the strength of a sound wave?

It's intensity

30

How is the intensity of a sound related to the square of the distance?

It is inversely proportional.

31

What is the effect of intensity on the way the human ear perceives sound?

Loudness

32

What unit of sound was created and named in honor of Alexander Graham Bell?

The bel

33

What smaller unit is commonly used instead of the bel?

The decibel

34

What is the effect of frequency on the way the human ear perceives sound called?

Pitch

35

What is sound that can be heard called?

Audible sound

36

What are sounds with pitches below the audible range called?

Infrasonic sounds (infra- "below", sonic- "sound")

37

What are sounds with pitches above audible range called?

Ultrasonic sounds (ultra- "beyond")

38

What is the change in frequency caused by an object's motion called?

The Doppler effect

39

What does the Doppler effect depend on?

Relative motion.

40

True or False:
The main factor affecting the speed of sound in air is the temperature of the air.

True

41

What are speeds above the speed of sound called?

Supersonic

42

What are speeds below the speed of sound called?

Subsonic

43

What numbers describe the speed of sound and are named after Ernst Mach?

Mach numbers

44

What is another name for a violent compression pulse?

A shock wave

45

What is the loud noise called that happens when the shock wave reaches the ear?

Sonic boom

46

What are the multiple reflections causing persistence of sound called?

Reverberation

47

What is a sound called that is heard distinctly after being reflected from some object?

An echo

48

True or False:
An echo cannot be heard if the source of the original sound is within 17 meters of the reflecting surface.

True

49

What does sonar stand for?

Sound navigation and ranging

50

What system was developed during World War II to locate submerged enemy submarines?

Sonar

51

What device uses pulses of ultrasonic sound to measure the depth of the water under a ship?

The depth finder

52

What is the procedure for calculating distance by measuring the tune interval that elapses between the sending of a sound wave and the return of an echo called?

Echo ranging

53

What type of sonar uses a narrow beam of ultrasonic waves to scan the ocean floor in a regular pattern?

Scanning sonar

54

What is the process of dissipating the energy of sound waves in matter known as?

Absorption

55

What is the study of sound?

Acoustics