Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PSYCH 3310: Sensation & Perception > Lecture 3: Waves, the Physics of Light & Sound > Flashcards

Lecture 3: Waves, the Physics of Light & Sound Flashcards

You may prefer our related Brainscape-certified flashcards:
Psychology 101 flashcards GRE® Psychology flashcards
1
Q

What is a wave?

A

Lights and sounds are composed of waves.

A wave is a type of internal motion of a medium, in which the displaced portion returns to equilibrium.

This disturbance propagates in space as well.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Wave

A

disturbance propagates in x…

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Transverse Waves

A

This is what occurs in the vibrations of stringed instruments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Longitudinal Waves

A

This is what occurs in the vibrations of wind instruments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Types of Waves

A

Transverse Waves – This is what occurs in the vibrations of stringed instruments.

Longitudinal Waves – This is what occurs in the vibrations of wind instruments.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Sound Waves

A

Sound waves involve the longitudinal oscillations of air molecules.

The sound vibrations in a long, narrow tube, such as a trombone, flute or trumpet, propagates in one direction.

In open air, a sound wave propagates radially in all directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Light Waves

A

Light waves involve transverse oscillations in electric and magnetic fields

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Light

A

A wave; a stream of photons, tiny particles that each consist of one quantum of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Diagram of a wave

A

All waves are caused by vibrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Velocity, Frequency and Wavelength

A

Within a given medium, light & sound waves travel at a constant velocity.

Thus, long wavelengths oscillate at low frequencies, and short wavelengths oscillate at high frequencies.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Long wavelengths oscillate at _____ frequencies.

A

low frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

short wavelengths oscillate at ____ frequencies.

A

high frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Two waves with the same velocity and different wavelengths will have different frequencies.

A

Two waves with the same frequency and different wavelengths will have different velocities

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Two waves with the same frequency and different wavelengths will have different velocities

A

Two waves with the same velocity and different wavelengths will have different frequencies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Interference

A

The addition and subtraction of waves

When 2 or more waves come together, the individual displacements at each point in space are added together to produce a composite wave.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Absorption

A

The conversion of energy to a different form, such as heat, when a wave hits an obstacle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Reflection

A

The reversal of direction when a wave hits an obstacle.

When a wave hits a boundary between two media, some of its energy rebounds in a different direction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Refraction

A

The bending of a wave as it crosses the boundary between two media

Refraction is what causes a pencil to appear bent when it is partially submerged in water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Diffraction

A

The bending of a wave around an obstacle

Waves can sometimes bend around obstacles.
Long wavelengths diffract more than short wavelengths.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Wave Interactions

A

Interference – The addition and subtraction of waves.

Absorption – The conversion of energy to a different form, such as heat, when a wave hits an obstacle.

Reflection – The reversal of direction when a wave hits an obstacle.

Refraction – The bending of a wave as it crosses the boundary between two media.

Diffraction – The bending of a wave around an obstacle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

When two or more waves come together, the individual displacements at each point in space are added together to produce a composite wave. This is referred to as ______.

A

interference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When a wave hits a boundary between two media, some of its energy may be converted to heat.

This is an exmple of….

A

Absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Scattered

A

Energy that is dispersed in an irregular fashion.

When light enters the atmosphere, much of it is absorbed or scattered and never reaches the perceiver.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

When a wave hits a boundary between two media, some of its energy rebounds in a different direction

A

Reflection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Some animals, such as bats, are able to use reflections of sounds to determine ______ .

A

the distance of objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Energy that is passed on through a surface (when it is neither reflected nor absorbed by the surface) is called ……

A

Transmitted energy

When a wave hits a boundary between two media, some of its energy may be transmitted across the boundary

27
Q

Transmitted

A

Energy that is passed on through a surface (when it is neither reflected nor absorbed by the surface)

When a wave hits a boundary between two media, some of its energy may be transmitted across the boundary

28
Q

What happens to a wave when it changes speed

A

Refraction

29
Q

When a wave travels from a less dense to a more dense medium at an angle off the line of normal, it _____ and bends ______ the line of normal.

A

When a wave travels from a less dense to a more dense medium at an angle off the line of normal, it *slows down and bends *towards the line of normal.

30
Q

When a wave travels from a more dense to a less dense medium at an angle off the line of normal, it ____ and bends *away from the line of normal.

A

When a wave travels from a more dense to a less dense medium at an angle off the line of normal, it *speeds up and bends *away from the line of normal.

31
Q

____ wave lengths refract MORE than _____ wavelengths.

A

Short wave lengths refract MORE than long wavelengths.

32
Q

Rainbows are caused by light that is _____ through particles of water.

A

Rainbows are caused by light that is refracted through particles of water.

33
Q

_____ wavelengths diffract more than _____ wavelengths

A

Long wavelengths diffract more than short wavelengths

34
Q

This animation shows diffraction through a slit.

A

It also shows how interference patterns can occur when a wave interacts with its own reflection.

35
Q

Natural Frequencies

A

Most objects have a specific frequency at which they vibrate most readily. This is called the natural or fundamental frequency.

For a vibrating string, the natural frequency increases with the tension of a string, and decreases with increasing length or mass.

For a vibrating tube, the natural frequency decreases with increasing tube length, and is higher for open tubes than for closed tubes.

The manipulation of these parameters is what allows musicians to play musical instruments.

Rule to remember: Short things have higher natural frequencies than long things

36
Q

Rule to remember:

A

Short things have higher natural frequencies than long things

37
Q

Methods of representing waves

A

Waveform plots
Spectral plots
Spectrograms

38
Q

Spectrum plots

A

Amplitude against frequency

The amplitudes of the sine waves give the amplitude spectrum of the sound.

The amplitude spectrum of a sine wave is a single point at the frequency of the sine wave.

39
Q

Waveform

A

Amplitude against time

Sound is a change in the pressure of the air.
The waveform of any sound shows how the pressure changes over time.

The eardrum moves in response to changes in pressure.

Any waveform shape can be produced by adding together sine waves of appropriate frequencies, amplitudes and phases.

40
Q

Sound is ….

A

….a change in the pressure of the air.

41
Q

The amplitudes of the sine waves give the amplitude spectrum of the sound.

A

The amplitude spectrum of a sine wave is a single point at the frequency of the sine wave.

42
Q

Amplitude is a measure of the pressure change of a sound and is related to how loud the sound is.

A

Amplitude squared is proportional to the energy or intensity (I) of a sound.

43
Q

complex sound

A

A sound which has more than one (sine-wave) frequency component

44
Q

periodic sound

A

which repeats itself at regular intervals

45
Q

A sine wave is a _____ sound

A

simple periodic

46
Q

_______ produce complex periodic sounds.

They have a spectrum consisting of a series of _____.

A

Musical instruments or the voice produce complex periodic sounds.

They have a spectrum consisting of a series of harmonics.

47
Q

fundamental frequency

A

The lowest frequency (of which all the others a re multiples)

48
Q

harmonics

A

Each harmonic is a sine wave that has a frequency that is an integer multiple of the fundamental frequency.

Musical instruments or the voice produce complex periodic sounds. They have a spectrum consisting of a series of harmonics.

49
Q

Here is 1/20th of a second of the waveform and also the spectrum of a complex periodic sound consisting of the first 4 harmonics of a fundamental of 100 Hz.

All the frequency components are integer multiples of 100 Hz.

A

A periodic sound consists of a section of waveform that repeats itself.

The period of the complex wave is the duration of this section.
In this case, it is 1/100s or 0.01s, or 10 ms.

The period is the reciprocal of the fundamental frequency (in this case 100 Hz).
If you change the period of a complex sound, you change its pitch.

Shorter periods - higher fundamental frequency - higher pitch.

50
Q

If you change the period of a complex sound, you change its _____.

A

If you change the period of a complex sound, you change its pitch.

51
Q

Integer multiples of the fundamental frequency

A

Harmonics

52
Q

Spectrograms

A

A spectrogram is a 3-dimensional plot of frequency and amplitude as a function of time. Amplitude is represented in a spectrogram by shades of gray

Spectrograms are especially useful for representing complex waveforms like speech that change over time.

53
Q

Properties of Waves

A

Amplitude: Controlled by the magnitude of the forces that started the wave

Frequency: f of oscillations: controlled by forces starting the wave and by the nature of the material or object that is oscillating

Spectral Composition: Refers to the mixture of different frequencies in a wave

54
Q

Amplitude

A

Controlled by the magnitude of the forces that started the wave

55
Q

Frequency f of oscillations

A

controlled by forces starting the wave and by the nature of the material or object that is oscillating

56
Q

Loudness

A

most related to intensity

57
Q

Timbre

A

most related to spectral composition

58
Q

The 3 Main Perceptual Attributes of Sound

A

The terms pitch, loudness, and timbre refer not to the physical characteristics of sound, but to the mental experiences that occur in the minds of listeners.

59
Q

The 3 Main Perceptual Attributes of Sound

A

The terms pitch, loudness, and timbre refer not to the physical characteristics of sound, but to the mental experiences that occur in the minds of listeners.

60
Q

The 3 Main Perceptual Attributes of Light

A

The terms Brightness, Hue, and Saturation refer not to the physical characteristics of light, but to the mental experiences that occur in the minds of observers.

61
Q

Brightness

A

most related to amplitude

62
Q

Hue

A

most related to wave length or frequency

63
Q

Saturation

A

most related to spectral composition

PSYCH 3310: Sensation & Perception (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions