Waves/Sounds

Question 1

What is Pulse?

Answer 1

A single vibratory disturbance in a medium

Question 2

What happens when a pulse travels down a string with velocity?

Answer 2

Energy is transferred to the string, which causes segments to vibrate up and down; creates an illusion of a continuous path

Question 3

What is the equation for the velocity of a pulse?

Answer 3

v=sqrt[T/(m/L)]

v=sqrt(TL/m)

Question 4

What do waves transfer?

Answer 4

Waves ONLY transfer energy

Question 5

What is the Principle of Superposition?

Answer 5

When two pulses at the same point and at the same time interact, the interaction produces a single pulse whose amplitude is equal to the sum of the displacement of the original two pulses

Question 6

What happens after the interaction of two pulses?

Answer 6

Both pulses continue in their original directions of motion, unaffected by the interaction

Question 7

What is Interference?

Answer 7

Superposition of waves of identical or opposite phases to produce constructive or destructive interference, respectively

Question 8

What is Constructive Interference?

Answer 8

When two pulses of identical phases (upward or downward) interact, creating a displacement larger than the original two; amplitudes add together

Question 9

What is Destructive Interference?

Answer 9

When two pulses with opposite phases (upward and downward) interact, creating a displacement smaller than the original two; amplitudes subtract

Question 10

In destructive interference, what happens when the two pulses have the same amplitude?

Answer 10

The interaction can cause the pulses to momentarily cancel out

Question 11

What is a Series of Waves?

Answer 11

Continuous up and down vibration given to a string that results in sets of transverse pulses; also known as a wave train

Question 12

Pertaining to waves, what is Frequency?

Answer 12

Number of waves per second (f)

Question 13

Pertaining to waves, what is Period?

Answer 13

Time required to complete one wave cycle (T)

Question 14

What is a Phase?

Answer 14

Relative position of a point on a wave with respect to another point on the same wave

Question 15

What does it mean for two waves to be “in phase”?

Answer 15

The two waves have the same frequency at the same point in time with no phase difference

Question 16

What is a Wave Length?

Answer 16

Distance between any two successive points (crest or trough) in phase; λ or lambda

Question 17

What is a Crest?

Answer 17

Peaks of a wave

Question 18

What is a Trough?

Answer 18

Valleys of a wave

Question 19

What is Amplitude?

Answer 19

Maximum displacement from rest position

Question 20

What is the equation for the velocity of a transverse wave?

Answer 20

v=fλ

Question 21

For sound, what does the amplitude of the wave represent?

Answer 21

Intensity or volume

Question 22

For sound, what does the frequency of the wave represent?

Answer 22

Pitch

Question 23

At the same amplitude, waves with higher frequencies transmit __________ energy per second.

Answer 23

More

Question 24

What is a Mechanical Wave?

Answer 24

Waves that result from the vibration of a physical medium (ie. drum, string, water); can be transverse or longitudinal

Question 25

What is a Longitudinal Wave?

Answer 25

A wave with regions of compressions and expansions that appear to travel parallel to the disturbances; also known as a compressional wave

Question 26

What is an example of a longitudinal wave?

Answer 26

Sound

Question 27

What is a Transverse Wave?

Answer 27

A wave that contains a vibration that travels perpendicular to the apparent direction of motion; equation: v=fλ

Question 28

What is a Standing Wave?

Answer 28

A wave in which incident and reflected waves combine to produce a wave that appears to be "standing" in one place

Question 29

What are Nodal Points?

Answer 29

Points that segment a standing wave; corresponds to points where no appreciable displacement takes place

Question 30

What is the Fundamental Mode of a wave?

Answer 30

First mode of a standing wave; easiest frequency mode of vibration possible; l=λ/2; contains zero nodal points

Question 31

As the nodes of a standing wave increase, what happens to its wave length?

Answer 31

Increases by λ/2 | 1 node= λ, 2 nodes= 3λ/2, etc.

Question 32

What is Resonance?

Answer 32

Buildup of wave energy due to constructive interference of standing waves; maximum transfer of energy from one body to another that shares the same natural vibrating frequency

Question 33

What is an Acoustical Wave?

Answer 33

Longitudinal wave in matter

Question 34

What are Beats?

Answer 34

When two sound waves interfere; the regions of constructive and destructive interference

Question 35

What is Frequency Difference?

Answer 35

Beats per second

Question 36

What is Path-Length Difference?

Answer 36

Something interference is dependent on; determines when interference is constructive or destructive

Question 37

What is the path-length difference of a constructive interference?

Answer 37

L1-L2=nλ; whole multiples (ie. 2, 4, 6)

Question 38

What is the path-length difference of a destructive interference?

Answer 38

L1-L2=(n+1/2)λ; odd multiples (ie. 1.5, 2.9, 3.4)

Question 39

What is Diffraction?

Answer 39

When a wave encounters a boundary, the wave appears to bend around the corner of the boundary; creates the illusion of waves bending

Question 40

What is the Doppler Effect?

Answer 40

As sound approaches a point, pitch (frequency) increases; when sound passes a point, pitch (frequency) decreases