Waves Flashcards

1
Q

What must the frequency of a sound wave be greater than to make it an ultrasound

A

20,000 Hz

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2
Q

2 types of reflection

A

Specular
Diffuse

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3
Q

Which type of reflection requires a rough surface

A

Diffuse

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4
Q

Which type of reflection requires a smooth surface

A

Specular

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5
Q

What can happen to light when it meets a new medium

A

Reflection, refraction, transmission, absorbtion

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6
Q

What do waves transfer from one place to another

A

Energy

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7
Q

True or false, waves transfer matter from one place to another

A

False, they transfer energy

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8
Q

True or false, waves transfer energy from one place to another

A

True

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9
Q

Which out of energy or matter do waves transfer from one place to another

A

Energy

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10
Q

To travel from one place to another the waves vibrate/ what

A

Oscillate

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11
Q

Another word for oscillate

A

Vibrate

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12
Q

What do waves do when they travel from one place to another

A

Oscillate/ vibrate

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13
Q

Word for maximum displacement (distance between undisturbed ‘sea’ level and highest/ lowest point of wave

A

Amplitude

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14
Q

True or false, one entire oscillation is equivalent to the wavelength

A

True

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15
Q

What is meant by time period of wave

A

Time it takes for one complete wave to pass a fixed point

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16
Q

Difference between wavelength on displacement distance graph vs displacement time graph for wave

A

Displacement time- wavelength represents time period (how long it takes for 1 oscillation/ 1 wave to pass)

Displacement distance- wavelength still represents oscillation but with no reference to how long it takes

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17
Q

True or false, 1 complete oscillation = 1 full wave

A

True

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18
Q

What is meant by frequency of wave

A

Number of complete waves per second

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19
Q

Name for number of waves per second

A

Frequency

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20
Q

Frequency vs time period

A

Frequency= number of waves per second
Time period= time taken for one complete wave to pass a fixed point

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21
Q

What unit is wavelength measured in

A

Metres

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22
Q

What unit is wave speed measured in

A

M/s

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23
Q

2 main types of wave

A

Transverse
Longitudinal

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24
Q

In transverse waves the oscillations are what to the direction the wave is moving

A

Perpendicular

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25
Q

In longitudinal waves the oscillations are what to the direction the wave is travelling

A

Parallel

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26
Q

In what type of wave are the oscillations parallel to the direction the wave is travelling

A

Longitudinal

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27
Q

In what type of wave are the oscillations perpendicular to the direction the wave is travelling

A

Transverse

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28
Q

True or false, the direction of energy transfer is the same as the direction the wave is moving

A

True

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29
Q

Are all electromagnetic waves longitudinal or transverse

A

Transverse

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30
Q

True or false, all electromagnetic waves are longitudinal

A

False
They’re all transverse

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31
Q

What type of wave are sound waves

A

Longitudinal

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32
Q

2 examples of longitudinal waves

A

Sound waves
P- seismic waves

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33
Q

Name for type of diagram used to show reflection taking place

A

Ray diagram

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34
Q

In reflection the angle of incidence is always equal to what angle

A

The angle of reflection

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35
Q

In reflection what 2 angles are always equal

A

Angle of reflection
Angle of incidence

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36
Q

Name for dashed line drawn perpendicular to boundary in ray diagram

A

Normal

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37
Q

What is the normal

A

Dashed line drawn perpendicular to boundary in ray diagrams

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38
Q

Should the normal be a solid or dashed line

A

Dashed

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39
Q

In reflection if the angle of reflection is 45 degrees then what’s the angle of incidence

A

45 degrees
(As they’re always equal)

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40
Q

In reflection which angle are are we already given/ have to measure

A

Angle of incidence
(Check answer)

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41
Q

What is the ‘point of incidence’

A

Point in ray diagram for reflection where incoming ray (incident ray) meets the boundary

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42
Q

What type of reflection is a mirror and why

A

Specular reflection
Mirror is a smooth surface so all rays come in at same angle and therefore are reflected at the same angle (normals are all in same direction)

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43
Q

What type of reflection is paper

A

Diffuse
(As it has a rough surface, even though it doesn’t seem like it)

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44
Q

What type of reflection is paper

A

Diffuse
(As it has a rough surface, even though it doesn’t seem like it)

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45
Q

True or false, in both specular (smooth surface) and diffuse (bumpy surface) reflection the light rays are all coming in from the same direction

A

True
However in diffuse reflection the normals will all be pointing in different directions as they have to be perpendicular to the surface which isn’t the same everywhere, therefore the light will be reflected in lots of different directions

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46
Q

Why is light reflected in lots of different directions in diffuse reflection

A

The normals are all pointing in different directions due to the surface being bumpy and they have to be 90 degrees to the surface (so even though the waves all come from the same direction, they will have to be reflected off in different directions)

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47
Q

Which type of reflection produces a clear image

A

Specular

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48
Q

True or false, in both Specular and diffuse reflection the angle of incidence is always equal to the angle of reflection

A

True

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49
Q

Waves travel at different what in different materials

A

Speeds

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50
Q

Why do waves travel at different speeds through different mediums

A

Different materials have different densities

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51
Q

Do waves travel faster or slower in denser materials

A

Slower

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52
Q

In what type of material do waves travel fastest

A

Low density
(They travel slower in higher densities)

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53
Q

Another word for material

A

Medium

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54
Q

If a wave travels from a less dense medium to a more dense medium what happens to its speed

A

Slows down
(As waves travel slower in higher densities)

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55
Q

Which is more dense out of air and glass

A

Glass
(so waves will travel slower in glass than air)

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56
Q

If a wave travelling from air into glass hits the boundary at a perpendicular angle then what happens

A

It will keep travelling straight through but just change speed due to the different densities
(It will only be refracted if it comes in to the boundary at an angle)

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57
Q

In what scenario will the wave bend towards the normal

A

Going from less dense to more dense

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58
Q

When a wave enters a more dense medium does it bend towards or away from the normal

A

Towards

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59
Q

When a wave enters a less dense medium does it bend towards or away from the normal

A

Away

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60
Q

When does a wave bend towards compared to away from the normal

A

Going into more dense= bends towards normal
Going into less dense= bends away from normal

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61
Q

True or false, when waves enter a different medium their wavelength also changes

A

True
As wave speed = frequency x wavelength
And frequency always stays the same

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62
Q

Does the frequency of the wave ever change

A

No

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63
Q

Does the wavelength of the wave ever change

A

Yes
When the wave passes through a different medium and changes speed as frequency never changes and
Wave speed= frequency x wavelength

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64
Q

When the wave speed changes e.g passing through a different medium which other aspect of the wave also changes

A

Wavelength
(As wave speed = frequency x wavelength)
(Frequency never changes)

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65
Q

When electromagnetic waves are travelling through a …, they all travel at the same speed

A

Vacuum (or air)

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66
Q

What speed do all EM travel at through a vacuum/ air

A

3 x10^8 m/s

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67
Q

7 types of EM waves

A

Radio waves
Microwaves
Infra-red waves
Visible light
Ultraviolet rays
X rays
Gamma rays

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68
Q

Electromagnetic waves transfer energy from what to what

A

Source, absorber

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69
Q

2 things EM waves are grouped by

A

Wavelength, frequency

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70
Q

Which EM wave has the highest frequency (and therefore shortest wavelength)

A

Gamma rays

71
Q

Which EM waves have the lowest frequency (and therefore longest wavelength)

A

Radio waves

72
Q

True or false, electromagnetic waves form a continuous spectrum

A

True

73
Q

Which is the only type of EM wave humans can see

A

Visible light

74
Q

2 uses of radio waves

A

Radios
TVs

75
Q

2 uses of microwaves

A

Cooking food
Satellite communication

76
Q

4 uses of infrared waves

A

Remote controls
Toasters
Electric heaters
Thermal image cameras

77
Q

1 use of visible light waves

A

Fibre optic communications

78
Q

2 uses of ultraviolet waves

A

Sun tanning
Security marking (e.g on passports/ banknotes)

79
Q

2 uses of X- rays and gamma rays

A

Medical imaging
Medical treatment

80
Q

What type of wave is used for medical imaging and treatment

A

Both X-rays and gamma rays

81
Q

Type of wave used for fibre optic communications

A

Visible light

82
Q

Type of wave used for sun tanning and security marking

A

Ultraviolet

83
Q

Type of wave used for radios and TVs

A

Radio waves (hence name)

84
Q

Type of wave used for cooking food and satelite communication

A

Microwaves
(Although infrared can also be used for cooking food in toaster)

85
Q

Type of wave used for remote controls, cooking food (toaster), thermal image cameras and electric heaters

A

Infrared

86
Q

2 types of wave used to cook food

A

Microwaves (microwave)
Infrared (toaster)

87
Q

Which type of EM wave can damage eyesight due to being very bright

A

Visible light

88
Q

Hazard of visible light

A

Very bright so can damage eyesight

89
Q

Hazard of ultraviolet waves

A

Can cause skin cancer/ premature skin ageing

90
Q

Which type of wave can cause skin cancer/ premature skin ageing

A

Ultra violet

91
Q

Which type of wave can cause burns

A

Infrared

92
Q

Hazard of infrared waves

A

Can cause burns

93
Q

Hazard of X-rays and gamma rays

A

Ionising radiation can cause cancer (but also treat it)

94
Q

Which type of wave can cause cancer (but also treat it)

A

X-rays and gamma rays

95
Q

Refractive index of glass

A

1.5
(Ratio quantity so no unit)

96
Q

Precision meaning

A

How close measured values are to the mean

97
Q

Name for how close measured values are to the mean

A

Precision

98
Q

Accuracy vs precision

A

Precision= how close measured values are to mean
Accuracy= how close measured values are to actual value

99
Q

What do EM waves transfer from their source to absorber

A

Energy

100
Q

.

A

.

101
Q

Why are microwaves suitable for cooking food and satellite communications

A

Can pass through Earth’s atmosphere to reach satellites
Can penetrate into food and are absorbed by the water molecules so heat it

102
Q

Why are infrared waves suitable for electric heaters, TV remotes, thermal image cameras and toasters (cooking food)

A

Can transfer energy quickly (so good for heating room/ food)
All hot objects emit this type of wave (infrared) so sensors can detect these to turn it into an image

103
Q

Why is visible light useful for fibre optic communications

A

Have short wavelength so can carry more information

104
Q

Why are X-rays and gamma rays good for medical imaging and treatment

A

Pass easily through flesh (but not denser materials like bones)
High dose kills living cells like cancer cells

105
Q

3 types of radio wave

A

Long wave
Short wave
Very short wave

106
Q

Which type of radio wave can be transmitted (passed from one place to another) long distances

A

Long waves and short waves

107
Q

Why can long waves (type of radio wave) be transmitted long distances

A

They diffract (bend) around the Earth’s surface

108
Q

What type of radio wave diffracts (bends) around the Earths surface

A

Long waves

109
Q

Why is it good if long waves (type of radio wave) can diffract (bend) around the earths surface

A

They can travel long distances

110
Q

True or false, both long waves and short waves (types of radio waves) can bend around the Earth

A

False
(Only long waves can)

111
Q

Which type of radio wave can diffract around the Earth’s surface

A

Long waves

112
Q

Which type of radio wave are reflected off the ionosphere (electrically charged layer of Earth’s upper atmosphere)

A

Short waves

113
Q

Ionosphere meaning

A

Electrically charged layer of Earth’s upper atmosphere

114
Q

Name for electrically charged layer of Earth’s upper atmosphere

A

Ionosphere

115
Q

Diffract meaning

A

Bend
E.g long waves (radio waves) diffract around the earth’s surface

116
Q

True or false, although short waves (radio waves) can travel long distances they can also be used to cover short distances

A

True
(E.g bluetooth)

117
Q

Example of short waves (radio waves) being used for short distance

A

Bluetooth

118
Q

Which type of radio wave is used for Bluetooth

A

Short wave

119
Q

What are very short radio waves used for

A

TVs and radios

120
Q

Which type of radio waves are used for TVs and radio

A

Very short waves

121
Q

Which type of radio wave travels directly from the transmitter to receiver

A

Very short waves

122
Q

Why is it bad in very short radio waves that they travel directly from the transmitter to the receiver

A

Tunnels/ hills etc can get in the way and make the signal bad e.g when you’re listening to the radio in the car

123
Q

Type of radio wave that can only travel in straight lines

A

Very short wave
(Long waves can bend around the Earth’s surface and short wave are reflected back and forth off the ionosphere)

124
Q

What type of current do radio waves create when they are absorbed by the receiver

A

Alternating current

125
Q

Use of oscilloscopes

A

Display frequency of an alternating current

126
Q

True or false, all microwaves can be absorbed by water molecules

A

False
Only some can

127
Q

Which type of microwaves are used for communications (satelites)

A

Ones that can’t be absorbed by water

128
Q

Why can only microwaves that aren’t absorbed by water be used for satelites

A

Satelites are high above the Earth
For the wave to get to the satelite it therefore needs to pass though the Earth’s atmosphere but the atmosphere contains water vapour
If it was absorbed by water vapour it would never reach the satelite

129
Q

How do microwaves work in heating up our food

A

Nearly all food contains water molecules so microwaves are used that can be absorbed by water
The microwaves are fired at our food
Energy from waves is absorbed by water molecules in food
Water molecules start to vibrate more so pass on energy to neighbouring non- water molecules
Energy then spreads through food by convection/ conduction

130
Q

What important molecule do foods contain that allows them to be heated up by microwaves

A

Water molecules (this is what absorbs the wave to allow the energy to be transferred)

131
Q

What in the food absorbs the microwave

A

Water molecule

132
Q

Why do foods higher in water heat up faster in microwaves

A

Water is what absorbs the wave
So the energy can be absorbed quicker and therefore spread through food quicker as more particles are vibrating

133
Q

True or false, microwaves can pass through the atmosphere

A

True
This allows them to reach satelites

134
Q

How do microwaves work in communication

A

Wave passes up through atmosphere to satelite
Satelite then sends signal back down to other point on earth that you’re communicating with (can be used to communicate with people on other side of world)

135
Q

If an object is hotter will it emit more or less infrared radiation

A

More

136
Q

For thermal imaging cameras will hotter objects that emit more infrared radiation (e.g animals/ criminals) be brighter or darker

A

Brighter

137
Q

Visible light appears different colours depending on the what

A

Wavelength

138
Q

Which colour of visible light is the has the longest wavelength

A

Red
(Violet is the shortest)

139
Q

What are optical fibres (used in fibre optic communications)

A

Thin glass/ plastic fibres that transmit pulses of light over long distances
(As the light is reflected every time it hits the surface of the fibre so just keeps on moving)

140
Q

Can optic fibres transmit light over long distances. Why/ why not

A

Yes
Optic fibre is very thin fibre of plastic/ glass- light is repeatedly reflected off surface so keeps going whole way through until it emerges out of the fibre

141
Q

Are fibre optic communications fast or slow

A

Fast

142
Q

Advantage of using optical fibres instead of copper wires (electricity)

A

Optical wires can transmit much more information
+ signals less likely to be distorted during transmission

143
Q

Why does UV light sterilise water

A

It kills microorganisms like bacteria

144
Q

How do X- rays work

A

X-rays are fired at patient
X-rays are absorbed by dense materials e.g bones
X-rays are transmitted through less dense materials e.g lungs/ intestines
The X-rays that pass through are detected by a detector plate to form an X-ray image

145
Q

Gamma rays are produced by changes in the what in the atom

A

Nucleus

146
Q

Radio waves are produced by what in an electrical circuit

A

Oscillations

147
Q

Radio waves are produced by oscillations in a what

A

Electrical circuit

148
Q

2 areas created on longitudinal wave due to the particles being squashed closer together/ pulled further apart

A

Rarefaction
Compression

149
Q

What is a wave

A

A disturbance that transfers energy from one region of the system to another

150
Q

Name for where air particles are squashed together in longitudinal wave

A

Compression

151
Q

Name for where air particles are spread apart in longitudinal waves

A

Rarefaction

152
Q

What frequency can humans hear between

A

20 Hz and 20,000Hz

153
Q

2 types of seismic waves

A

P- waves
S- waves

154
Q

Which type of seismic waves are transverse and which are longitudinal

A

P- waves= longitudinal
S- waves= transverse

155
Q

Type of seismic wave that pushes and pulls material

A

P- waves
(As they’re longitudinal)

156
Q

Type of seismic wave that shakes material side to side

A

S- wave

157
Q

Can S- waves travel through a liquid

A

No, only a solid

158
Q

Which type lf seismic wave can travel through solids only, not liquids

A

S- waves

159
Q

Which type of seismic wave can travel through both solids and liquids

A

P- waves

160
Q

Seismologists use data received at monitoring stations around the Earth to do what

A

Determine size of core
Determine structure of Earth

161
Q

Which layers of the earth are liquids and which are solids out of inner core, outer core, mantle and crust

A

Inner core, mantle and crust = solid
outer core = liquid

162
Q

Which type of seismic wave can’t pass through the outer core and why

A

S- waves
Outer core is liquid
S- waves can only travel through solids not liquids

163
Q

Each colour in the visible light spectrum has its own narrow band of what

A

Wavelength and frequency

164
Q

3 primary colours

A

Red
Blue
Green

165
Q

3 secondary colours

A

Cyan (blue/ green)
Magenta (purple/ pink)
Yellow

166
Q

Colour filters work by absorbing certain what and transmitting other wavelengths (colours)

A

Wavelengths (and therefore colours as different colours have different wavelengths)

167
Q

How do colour filters work

A

Absorb certain wavelengths (and therefore colours)
Transmit other wavelengths (and therefore colours)

168
Q

Why don’t white or black appear on the visible light spectrum

A

Black is simply the absence of (visible) light
White is a combination of all the wavelengths (colours)

169
Q

Purpose of ripple tank RPA

A

Measure speed of wave in a liquid

170
Q

The ripple tank RPA measures the speed of a wave in a what

A

Liquid

171
Q

Wave speed RPA measuring frequency and wavelength method

A

1) set up a ripple tank and turn on the overhead lamp and electric motor
2) place a 30cm ruler in the ripple tank perpendicular to the oscillating paddle (so that it’s perpendicular to the direction the waves are travelling)
3) Take a picture of the projected image
4) Use the ruler to measure the wavelength of 10 waves and divide by 10 to find mean wavelength (improves accuracy)

(Now you have wavelength)

1) Place a stopwatch next to the ripple tank
2) Take a slow motion video of the waves moving alongside the stopwatch
3) Count the number of waves that pass a fixed point in 10 seconds using the stopwatch in the video
4) Divide number of waves counted in 10s by 10 to get frequency (number of waves passing fixed point per second)

(Gets frequency)

Multiply frequency by wavelength to get wave speed

172
Q

Wave speed RPA all in one method

A

1)Set up ripple tank and turn on overhead lamp and electric motor
2)place ruler next to tank perpendicular to the oscillating paddle
3) Place stopwatch next to tank
4) Turn on stopwatch and take slow motion video with stopwatch in
5) Mesure length of tank with ruler
6) Using slow motion video measure time it takes for 1 wave to travel length of tank
7) Calculate wave speed by doing distance/time
8) To improve accuracy repeat whole process to find mean wave speed and reduce effect of random errors

173
Q

In wave ripple tank RPA why are all the wave speeds similar but not identical

A

Although waves move at the same speed in water it’s hard to see exactly where the waves are and be 100% accurate with measurements as the waves keep moving and some are reflected