Unit 4 - Waves & Sound

Question 1

Amplitude (A)

Answer 1

displacement from equilibrium (m)

Question 2

Wavelength (λ)

Answer 2

length of a wave/cycle; from crest to crest or trough to trough (m)

Question 3

Period (T)

Answer 3

time per cycle (sec/cycle)

Question 4

Frequency (f)

Answer 4

cycles per second (Hz)

Question 5

Cycle

Answer 5

the pattern that repeats (m)

Question 6

Trough

Answer 6

the lowest point

Question 7

Crest

Answer 7

the highest point

Question 8

Phase

Answer 8

the position of the wave in the x-axis

Question 9

Vibration

Answer 9

the cyclical motion of an object about an equilibrium point

Question 10

Mechanical Wave

Answer 10

the transfer of energy through a material due to vibration

Question 11

Transverse Wave

Answer 11

particles move perpendicular to the energy

Question 12

Longitudinal Wave

Answer 12

particles move parallel to the energy

Question 13

Compression

Answer 13

area of longitudinal waves where the particles come together

Question 14

Rarefaction

Answer 14

area of longitudinal waves where the particles are further apart

Question 15

Frequency Range Detected by Humans

Answer 15

20 Hz. to 20,000 Hz.

Question 16

Sound is a ________ wave.

Answer 16

longitudinal

Question 17

Two Factors that Affect the Speed of Sound

Answer 17

density and stiffness of medium

Question 18

Infrasonic

Answer 18

lower frequency than a human can hear

Question 19

Ultrasonic

Answer 19

higher frequency than a human can hear

Question 20

Mach Number

Answer 20

describes speed relative to the speed of sound

Question 21

Sound Intensity

Answer 21

the amount of sound energy being transferred per unit area (watts/m^2)

Question 22

Decibel (dB)

Answer 22

a logarithmic unit scale to describe the human range of sound intensities

Question 23

The Doppler Effect

Answer 23

an apparent change in the frequency of sound waves, occurring when the source and the observer are in motion relative to each other

Question 24

Vsource must be…

Answer 24

negative if coming, positive if going (towards stationary observer)

Question 25

Media Boundary

Answer 25

the location where two or more media meet

Question 26

Free-End Reflections

Answer 26

both ends are free; reflections have same orientation as original wave

Question 27

Fixed-End Reflections

Answer 27

one end is fixed; reflections are inverted

Question 28

high density -> low density

Answer 28

reflected, same orientation

Question 29

low density -> high density

Answer 29

reflected and inverted

Question 30

Standing Wave

Answer 30

an interference pattern produced when incoming and reflected waves interfere with each other

Question 31

Node

Answer 31

the location where the particles in the medium are at rest

Question 32

Antinode

Answer 32

the location where the particles in the medium are moving at the greatest speed; the amplitude will be twice that of the original wave

Question 33

Fundamental Frequency (1st Harmonic)

Answer 33

the lowest frequency that can produce a standing wave in a given medium

Question 34

Harmonics

Answer 34

whole-number multiples of the fundamental frequency

Question 35

Media with two fixed/two free ends.

Answer 35

Ln=nλ/2

Question 36

Media with one fixed end.

Answer 36

Ln=(2n-1)λ/4

Question 37

Damping

Answer 37

a reduction in the amplitude of a wave as a result of energy absorption (air resistance or friction) or destructive interference

Question 38

Resonant Frequency

Answer 38

the frequency at which a medium vibrates most easily

Question 39

Resonance

Answer 39

a condition in which the frequency of a wave equals the resonant frequency of the wave’s medium

Question 40

Interference

Answer 40

the process of generating a new wave when two or more waves meet

Question 41

Principle of Superposition

Answer 41

states that at any point the amplitude of two interfering wave is the sum of the amplitude of the individual waves

Question 42

Constructive Interference

Answer 42

when waves combine to form a wave with a greater amplitude

Question 43

Destructive Interference

Answer 43

when waves combine to form a wave with a lesser amplitude