6. Waves Flashcards

1
Q

What type of wave is a sound wave?

A

Longitudinal

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2
Q

Which type of vibrations move parallel to the direction of the wave?

A

Longitudinal

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3
Q

Which type of vibrations move perpendicular to the direction of the wave?

A

Transverse

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4
Q

Which waves can’t travel through a vacuum?

A

Mechanical

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5
Q

Which waves can travel through a vacuum?

A

Electromagnetic

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6
Q

Which waves pass their vibrations through particles?

A

Mechanical

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7
Q

What is frequency measured in?

A

Hertz

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8
Q

If one wave passes per second, what is the frequency?

A

1 Hz

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9
Q

How do you work out frequency?

A

Frequency = 1 / Period

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10
Q

What is a period?

A

How long is takes for the wave to pass a point - messed in seconds

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11
Q

Equation for wave speed?

A

Wave speed = frequency x wavelength

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12
Q

Equation for frequency?

A

Frequency = speed / wavelength

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13
Q

Equation for wavelength?

A

Wavelength = speed / frequency

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14
Q

What is the symbol for wavelength?

A

Lambda

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15
Q

What does the angle of incidence equal?

A

The angle of reflection

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16
Q

When light enters a glass cube, which direction does it refract?

A

Towards the normal

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17
Q

What happens when light enters a denser glass block?

A

The speed of the wave decreases and it refracts towards the normal

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18
Q

When the incident ray leaves the glass block, which direction does it go in?

A

Away from the normal

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19
Q

What happens to the speed of the ray it leaves the glass block?

A

It speeds up and bends away from the normal

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20
Q

What is the speed of a wave through a vacuum?

A

300,000,000 or 3x10 to the power of 8

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21
Q

Do different electromagnetic waves carry different amount of energy?

A

Yes

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22
Q

What happens when a ray is absorbed instead of reflected?

A

It heats up

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23
Q

What happens as the energy of a wave increases?

A

The temperature and hazard increased

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24
Q

What happens as the wavelength decreases?

A
The frequency increases
The energy carried increases 
The waves become more dangerous
The waves diffract less
The waves have a shorter range
The waves carry more information
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25
Q

What are the groups in the electromagnetic spectrum?

A
Gamma
X-ray
Ultraviolet 
Visible
Infrared 
Microwaves
Radio waves
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26
Q

What type of electromagnetic wave has the highest frequency and energy, and the shortest wavelength?

A

Gamma

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27
Q

What type of electromagnetic wave has the lowest frequency and energy, and the longest wavelength?

A

Radio waves

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28
Q

What are infrared waves used for?

A

To locate fire, detect humans and night vision

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29
Q

What type of wave is a light wave?

A

Transverse

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30
Q

What are radio waves used for?

A

Radio, TV, telecommunications

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31
Q

What are gamma waves used for?

A

Kills bacteria, radiotherapy, cancer treatment

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32
Q

What are microwaves used for?

A

Radar detection, satellite communications, cooking

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33
Q

What are in X-rays used for?

A

Examine damaged machinery and medical scans

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34
Q

What are visible waves used for?

A

Computers, TV, LED display, to see

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35
Q

What are ultraviolet waves used for?

A

Detect counterfeit banknotes

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36
Q

What are the hazards of infrared waves?

A

Overheating - burning

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37
Q

What are the hazards of radio waves?

A

None

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38
Q

What are the hazards of gamma waves?

A

Cancer mutations to tissue

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39
Q

What are the hazards of microwaves?

A

Damage parts of brain

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40
Q

What are the hazards of X-Ray’s?

A

Body cells can be killed by high doses

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41
Q

What are the hazards of visible waves?

A

Intense beam damages eyes

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42
Q

What are the hazards of ultraviolet waves?

A

Sun burn, skin cancer

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43
Q

How are sounds made?

A

When an object vibrates and it causes the layer of air next to it to vibrate

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44
Q

Where do sounds travel fastest? Why?

A

Solids because the particles are closer together

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45
Q

Why is the no sound in a vacuum?

A

Because there are no particles to vibrate and pass on energy

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46
Q

What do you need to remember when doing f=v/lambda

A

MAKE SURE THAT THE WAVELENGTH IS IN METRES, THE TIME IN SECONDS AND FREQUENCY IN HZ

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47
Q

What is the range of normal human hearing?

A

20Hz to 20,000Hz

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48
Q

When will sound waves refract?

A

When air changes temperature (change in medium) - waves will travel slower in cooler air

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49
Q

Where does sound refract in the night?

A

Downwards, the air near the ground is cooler than the air higher up

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50
Q

What frequency are ultrasound waves?

A

Higher than 20,000Hz

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51
Q

When are ultrasound waves reflected?

A

When they reach a boundary between two different media

52
Q

How do you determine how far away a boundary is?

A

How long the reflections take to reach the detector

53
Q

What is ultrasound used for?

A

Medical

Industrial cleaning and no destructive testing of materials

54
Q

Why does the ultrasound need to be a pulse?

A

So you can hear the echo

55
Q

How is the time delay for an ultrasound and pulse worked out?

A

distance = speed x time

56
Q

Why is gel used in ultrasound?

A

Because then there is more ultrasound absorbed. When there is a big difference between densities lots of it would be reflected.

57
Q

What is the distance in ultrasound?

A

The way there and back

58
Q

What is the depth in ultrasound?

A

Just the way there

59
Q

Other uses of ultrasound?

A

The detection and removal of kidney stones

60
Q

What makes seismic waves?

A

A sudden release of energy in the earths crust

61
Q

What is used to detect movements of the earths crust?

A

A seismometer

62
Q

What are the two types of seismic wave?

A

Primary and secondary

63
Q

Properties of primary waves?

A
  • longitudinal
  • travels through solids and liquids
  • travels faster
64
Q

Properties of secondary waves?

A
  • transverse
  • only travel through solids
  • travels slower
65
Q

How does heat travel through space?

A

By infrared waves

66
Q

What emits and absorbs thermal radiation?

A

All bodies

67
Q

What is thermal (infrared) radiation?

A

The transfer of energy by electromagnetic waves

68
Q

What is a thermograph?

A

The images taken using infrared radiation

69
Q

What surface is the best emitter of infrared radiation?

A

Matte black surfaces

70
Q

What surface is the worst emitter of infrared radiation?

A

Silver (shiny) surfaces

71
Q

Best materials to emit infrared radiation? Best to worst

A

Matte black, shiny black, white, silver

72
Q

Which kettle will cool down faster: black or metallic?

A

Black because it will emit more radiation

73
Q

What direction does heat energy flow in?

A

From a hot object to a cooler one

74
Q

What do good emitters also act as?

A

Good absorbers

75
Q

What surface is the best absorber of infrared radiation?

A

Matte black surfaces

76
Q

What surface is the worst absorber of infrared radiation?

A

Silver surfaces

77
Q

Best materials to absorb infrared radiation? Best to worst

A

Matte black, shiny black, white, silver

78
Q

Why are shiny surfaces the worst absorbers?

A

They reflect most of the radiation away

79
Q

Why do solar panels have a black outer layer?

A

So it can absorb heat

80
Q

Why are firefighters suits shiny?

A

They are the worst absorbers, the the best reflectors

81
Q

Why is the back of a solar panel silver?

A

Reflect heat back onto pipes

82
Q

Why are premature babies wrapped in silver blankets?

A

Its the worst emitter, so reduces the amount of heat that they lose

83
Q

Why are radiators in car engines black?

A

It’s the best emitter

84
Q

What is a perfect black body?

A

An object that absorbs all the radiation that hits it

85
Q

What does a perfect black body not do?

A

Reflect or transmit any radiation

86
Q

What is the radiation emitted by a black body called?

A

Black body radiation

87
Q

What is black body radiation?

A

The radiation emitted by a black body

88
Q

If an object’s temperature is higher, what will happen to the infrared radiation it’s emitting?

A

Higher temperature -> more infrared radiation emitted in a given time

89
Q

What happens as a filament lamp warms up?

A
  • doesn’t glow, emits infrared
  • warms up glows dull red -> emitting visible spectrum
  • orange-red
  • yellow-white as filament gets hotter
90
Q

What does the intensity of radiation at a certain wavelength depend on?

A

Temperature

91
Q

What happens as temperature and radiation increases?

A

Radiation increases at every wavelength and the peak moves to a shorter wavelength (high frequency)

92
Q

What happens to radiation as temperature increases?

A

If temperature increases, intensity of radiation increases at every wavelength so peak moves to a shorter wavelength

93
Q

What does the temperature of the earth depend on?

A
  1. The rate that light and infrared radiation are absorbed by the atmosphere/surface or are reflected back into space
  2. The rate at which the earth emits radiation from its surface and atmosphere
94
Q

Where does the sun’s spectrum peak?

A

At visible wavelengths

95
Q

What are the two major types of lens?

A
  • concave

* convex

96
Q

What can concave lenses also be known as?

A

Diverging lenses

97
Q

What can convex lenses also be known as?

A

Converging lenses

98
Q

When is there a principal focus?

A

When the light rays are parallel

99
Q

In a convex lens, how does the thickness of the lens affect the focal length?

A

The thicker the lens, the shorter the focal length

100
Q

What is the shape of a converging lens?

A

It is thicker at the centre than the edges

101
Q

What is the shape of a diverging lens?

A

It is thinner at the centre than the edges

102
Q

How is magnification calculated?

A

magnification = image height / object height

103
Q

If the image is larger than the object what is the magnification equal to?

A

greater than 1

104
Q

If the image is smaller than the object what is the magnification equal to?

A

less than 1

105
Q

What can the image in a convex lens be?

A
  • real or virtual
  • magnified or diminished
  • upright or inverted
106
Q

How is the image transformed in a camera?

A

(convex lens)

  • diminished
  • inverted
  • real
107
Q

How is the image transformed in a projector?

A

(convex lens)

  • magnified
  • inverted
  • real
108
Q

How is the image transformed in a magnifying glass?

A

(convex lens)

  • magnified
  • upright
  • virtual
109
Q

What type of images do convex lenses give?

A
  • virtual
  • upright
  • diminished
110
Q

What happens in a convex lens when the object moves further away from the lens?

A

The image gets smaller and moves away from the lens

111
Q

How is short-sightedness corrected?

A

The eyeball is elongated so needs a concave lens

112
Q

How is long-sightedness corrected?

A

Convex lens

113
Q

Why does white light spread out into colours after it passes through a glass pyramid?

A

The different wavelengths experiences different changes in speed as they enter and leave the glass so refract by different amounts

114
Q

Which colours are refracted the most and the least?

A
  • red is refracted the least

* violet is refracted the most

115
Q

What are the primary colours of light?

A

Red, green, blue

116
Q

What are the secondary colours of light?

A

Yellow, cyan, magenta

117
Q

What does green and blue light create?

A

Cyan light

118
Q

What does green and red light create?

A

Yellow light

119
Q

What does green and red light create?

A

Magenta light

120
Q

What does a filter do?

A

Only allows a small range of wavelengths to pass through

121
Q

What does a red filter do?

A

Only allows red light through and absorbs blue and green light

122
Q

What are opaque objects?

A

Those that do not transmit light

123
Q

What does the colour that an objects appears depend on?

A

Which wavelengths are most strongly reflected

124
Q

Why do objects appear white?

A

They reflect all of the wavelengths of visible light equally

125
Q

Why does a red object look black through a blue filter?

A

A red object only reflects red light and the blue filter only transmits blue light, so only blue light shines on the red object and it is absorbed so it appears black

126
Q

How is a light ray reflected by flat foil?

A

Reflected in a single direction (specular reflection)

127
Q

How is a light ray reflected by crumpled foil?

A

Scattered (diffuse reflection)