P6 - Waves Flashcards

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1
Q

What is amplitude?

A

The maximum displacement of a point on a wave, away from it’s undisturbed position.

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2
Q

What is frequency?

A

The number of waves passing a particular point per second.

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3
Q

What is wave length?

A

The distance from one point on one wave to the equivalent point on an adjacent wave.

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4
Q

What is wave length measured in?

A

Lambda.

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5
Q

What is a period?

A

The time it takes for a wave to complete a full cycle.

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6
Q

What is amplitude measured in?

A

Amps (A)

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7
Q

What is frequency measured in?

A

Hertz (Hz)

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8
Q

What are the 2 types of waves?

A

Longitudinal and transverse.

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9
Q

What is a longitudinal wave?

A

When the oscillations are parallel to the direction of energy transfer.

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10
Q

What is a transverse wave?

A

The oscillations are perpendicular to the direction of energy transfer.

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11
Q

What is an oscillation?

A

A vibration about a rest posistion.

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12
Q

What is Echo sounding?

A

Used to detect objects in deep water and detect water depth.

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13
Q

What is the limit of human hearing?

A

20,000 Hz (anything above this is called an ultrasound)

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14
Q

How do you measure wave length?

A

Place a metre ruler perpendicular to the waves shown on the card.
Measure across as many waves as you can.
Divide that length by the total number of waves.

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15
Q

How do you measure wave frequency?

A

Count the number of waves passing a chosen point over a given time.
Divide the number of counted waves by the given time period.

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16
Q

What is the normal?

A

An imaginary line drawn perpendicular to the plane.

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17
Q

What is the angle of incidence?

A

The angle between the incident (incoming ray) and the normal.

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18
Q

What is the angle of reflection?

A

The angle between the reflected ray (outgoing ray) and the normal.

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19
Q

What is a rule linking the angle of incidence and the angle of reflection?

A

Angle of incidence = angle of reflection

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20
Q

What is a specular reflection?

A

When a reflection surface is smooth so, waves are reflected in a single direction.

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21
Q

What is diffuse reflection?

A

When a reflection surface is rough, scattering occurs, meaning waves are reflected in different directions.

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22
Q

What is refraction?

A

The change of direction caused by waves changing speeds as they enter a different material.

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23
Q

What happens when a ray enters a more dense material?

A

It slows and moves towards the normal.

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24
Q

What happens when a ray enters a less dense material?

A

It speeds up and moves away from the normal.

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25
Q

Give 2 examples of transverse waves.

A

Electromagnetic waves.
Seismic s-waves.

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26
Q

Give 2 examples of longitudinal waves.

A

Sound waves.
Seismic p-waves.

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27
Q

What are the two parts of a longitudinal wave called?

A

Compressions and rarefactions.

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28
Q

What is meant by frequency 200 Hz?

A

200 waves pass a point per second.

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29
Q

What is wave speed?

A

The speed at which a wave moves or energy is transferred through a medium.
Meters traveled per second.

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30
Q

What does a wave transfer?

A

Energy.

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31
Q

How do you calculate wave speed?

A

Wave speed = Frequency x wave length

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32
Q

What is wave speed measured in?

A

m/s

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33
Q

How do sound waves travel though a solid?

A

The particles in a solid vibrate and transfer kinetic energy through a material.

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34
Q

What is the frequency range of human hearing?

A

20 Hz - 20 kHz

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35
Q

Give an example use for ultrasound waves?

A

Medical or industrial imaging.

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36
Q

What natural event produces seismic waves?

A

Earthquakes - produces both p-waves and s-waves.

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37
Q

What medium can p-waves travel through?

A

Solids and liquids.

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38
Q

What medium can s-waves travel through?

A

Only solids.

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39
Q

How does echo-sounding work?

A

High-frequency sound waves are emitted, reflected and detected.
Time difference between emission and detection (alongside wave speed) are used to calculate distances.

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40
Q

What are the 2 types of seismic waves?

A

P-waves and S-waves

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41
Q

What is the purpose of the pinna?

A

Gathers sound waves from the environment and directs them into the ear canal, where they cause the ear to vibrate.

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42
Q

What are the “small bones” names?

A

Hammer, anvil and the stirrup.

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43
Q

What is the function of the “small bones”?

A

Transmit vibrations to the cochlea.

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44
Q

What does the cochlea do?

A

Converts these vibrations into electrical signals.

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45
Q

What does the auditory nerve do?

A

Transport the electrical signals to the brain.

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46
Q

What seismic wave has a faster wave speed?

A

P-waves.

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47
Q

How do we know the mantel is solid from the study of seismic waves?

A

Both P-waves and S-waves can travel through.

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48
Q

How do we know the outer core is liquid from the study of seismic waves?

A

P-waves are refracted indicating a change in density.
S-waves don’t pass through.

49
Q

How do we know the inner core is liquid from the study of seismic waves?

A

P-waves are refracted again, indicating a different medium.

50
Q

What does the speed of seismic waves through a material depend on?

A

The density of the medium of which they travel through.

51
Q

Order the types of electromagnetic radiation from lowest to highest frequency?

A

Radio waves.
Microwaves.
Infrared.
Visible light.
Ultraviolet.
X-rays.
Gamma rays.

52
Q

How do the speeds of EM radiation differ in a vacuum and in air?

A

EM waves all travel at the same speed in a vacuum and in air.

53
Q

What property of waves in different mediums causes refraction?

A

Velocity.
Wave speed is slower in denser materials, causing refraction.

54
Q

What type of waves can be produced by oscillations in an electrical circuit?

A

Radio waves.

55
Q

What are EM waves?

A

Transverse waves that transfer energy from the wave source to the absorber.

56
Q

What type of spectrum to EM waves form?

A

A continuous spectrum of different wavelengths but are grouped in order of their wavelength and frequency.

57
Q

What do we know about the waves at the lower end of the EM spectrum?

A

Long wavelength.
Low frequency.
Low energy.

58
Q

What do we know about the waves at the upper end of the EM spectrum?

A

Short wavelength.
High frequency.
High energy.

59
Q

How are radio waves produced?

A

Oscillating electrons.

60
Q

What are the 2 types of radio waves?

A

Short waves.
Long waves.

61
Q

Why can long wave radio signals travel long distances?

A

Because they diffract and follow the curvature of the earth.

62
Q

Why can short wave radio signals travel long distances?

A

They do not diffract, but they reflect of the ionsphere.

63
Q

Why are microwaves useful?

A

Because they are not absorbed by the atmosphere, so they can be used to transmit signals to and from satellites.

64
Q

Where are radio waves used?

A

To transmit television, radio and commercial signals.

65
Q

Where is infrared radiation used?

A
  1. Electrical heaters
  2. Cooking food
  3. Infrared cameras and detectors.
66
Q

How do X-rays work?

A

High frequency rays that are absorbed by dense body parts, such as bones, but pass through soft tissue.

67
Q

Where are X-rays used?

A

In medical imaging.

68
Q

When are gamma rays emitted?

A

When a nucleus becomes unstable.

69
Q

What 3 types of EM waves have dangerous effects on body tissue?

A

Ultraviolet waves, X-rays and gamma rays. (top 3 on EM spectrum)

70
Q

What can high-frequency EM waves do to the body?

A

Cause mutations to DNA which can lead to cancer.

71
Q

What can ultraviolet waves do to the skin?

A

Cause it to age prematurely. Increase the risk of developing skin cancer.

72
Q

What type of radiation are X-rays and gamma rays?

A

Ionising radiation, can cause cancer.

73
Q

How many millisieverts in 1 sievert?

A

1000.

74
Q

What is the velocity of all EM waves in a vacuum?

A

3 x 10 (power of 8)

75
Q

What type of EM radiation transfers the most energy?

A

Gamma rays.

76
Q

What type of EM radiation does every object emit?

A

Visible light.

77
Q

How do microwaves heat up food?

A

Water molecules in food absorb the microwave causing it to heat up.

78
Q

What is ultraviolet absorbed by?

A

The skin.

79
Q

How can radio waves create an alternating current in a circuit?

A

When radio waves are absorbed, they can induce oscillations in a circuit with the same frequency as the waves themselves.

80
Q

Two examples of where microwaves are used.

A
  1. Satellite communications.
  2. Cooking food.
81
Q

What wave phenomenon is used by lenses to form an image?

A

Refraction.

82
Q

How does a convex lens form an image?

A

Parallel rays of light are refracted and brought together at a point.

83
Q

What is a name for the point at which rays of light are brought together?

A

Principle focus.

84
Q

What is meant by the focal length of a lens?

A

The distance from the lens to the principle focus.

85
Q

What is the difference between the image produced of convex lenses and concave lenses?

A

Convex lenses can produce real or virtual images.
Concave lenses only produce virtual.

86
Q

What determines the colour of visible light waves?

A

The wavelength and the frequency of the light waves.

87
Q

What colour of visible light has the highest frequency?

A

Blue.

88
Q

What colour of visible light has the longest wavelength?

A

Red.

89
Q

How does a red colour filter work?

A

It absorbs all wavelengths of light other than those in the red range of the spectrum.
Meaning only red light passes through the filter.

90
Q

What colour does an object appear if all wavelengths are reflected by equal amounts?

A

White.

91
Q

What colour does an object appear if all wavelengths are absorbed?

A

Black.

92
Q

What determines the colour of an object?

A

Different objects reflect different wavelengths of light by different amounts.
The wavelengths that are most strongly reflected determine the colour.

93
Q

What happens to the wavelengths of light that aren’t reflected by an object?

A

They are absorbed by the object.

94
Q

What do all bodies (objects) emit and absorb and why?

A

Infrared radiation. Because of the energy in their thermal energy stores.

95
Q

What happens when an object is hotter than it’s surroundings?

A

It will emit more radiation than it absorbs, meaning it’s temperature will decrease.

96
Q

What is a perfect black body?

A

An object that absorbs all radiation that is incident on it.

97
Q

How much radiation does a perfect black body reflect or transmit?

A

None.

98
Q

Why is a perfect black body the best possible emitter of radiation?

A

A perfect absorber is a perfect emitter.

99
Q

What 2 things depend on the temperature of an object?

A
  1. Wavelength
  2. Intensity of radiation emitted.
100
Q

What can be said about the rates for absorption and emission for a body at a constant temperature?

A

The body is absorbing and emitting at the same rate.

101
Q

What can be said about the rates for absorption and emission for a body increasing in temperature?

A

It is absorbing it faster than it is emitting it.

102
Q

Give 2 factors that effect the temperature of the Earth.

A
  1. The Earth’s rate of absorption and emission of radiation.
  2. Amount of reflection into space.
103
Q

Does a hotter object or a cooler object emit more radiation, in a given time?

A

Hotter object.

104
Q

How does temperature link to wavelength?

A

Very hot objects emit shorter wavelength radiation than cooler objects.

105
Q

What happens to the amount of short wavelength radiation emitted as the object gets hotter?

A

More short wavelength radiation is emitted.

106
Q

What happens to the intensity of the radiation at higher temperatures?

A

It increases.

107
Q

What does transmitted mean?

A

Passed through.

108
Q

What happens when an object is cooler than it’s surroundings?

A

It will absorb more radiation than it emits. So it’s temperature will increase.

109
Q

What type of radiation does the sun emit?

A

Short wavelength radiation such as visible light and ultraviolet.

110
Q

What (on earth) reflects radiation?

A

Clouds.

111
Q

What happens to the radiation that is not reflected by the clouds?

A

Absorbed by the earth, causing it to heat up, and then emitted back into space.

112
Q

What process traps the energy that is emitted back into space?

A

The greenhouse effect.

113
Q

What does human activities mean for the Earth/ greenhouse effect?

A

More heat energy is trapped and less is radiated into space.

114
Q

How can cloud cover mean that less energy is radiated into space?

A

Clouds can reflect infrared back to earth and prevent it from being radiated into space.

115
Q

What part of the spectrum is the radiation emitted from the Earth’s surface in?

A

Infrared.

116
Q

What is the net result of the greenhouse effect?

A

That the temperature of the Earth increases until there is the same amount of incoming radiation as there is outgoing radiation.

117
Q

What is the difference between wave frequency and speed?

A

Wave speed is meters traveled per second.
Wave frequency refers to the number of cycles per second.

118
Q

Where is velocity slowest - shallow or deep water?

A

Shallow