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Physics GCSE > Section 2 - Waves and the Electromagnetic Spectrum > Flashcards

Section 2 - Waves and the Electromagnetic Spectrum Flashcards

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1
Q

What happens when a wave travels through a medium?

A

The particles of the medium vibrate and transfer energy and information between each other

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2
Q

What do waves transfer?

A

Energy and information

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3
Q

What doesn’t change when a wave travels through a medium?

A

The particles location

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4
Q

What is the amplitude of a wave?

A

The displacement from the rest position to a crest or trough

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5
Q

What is the wavelength of a wave?

A

The length of a full cycle of the wave

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6
Q

What is the frequency of a wave?

A

The number of complete cycles of the wave passing a certain point per second

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7
Q

What is the period of a wave?

A

The number of seconds per cycle

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8
Q

What is the relationship between frequency and the period of a wave?

A

They are inverse

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9
Q

What is the period equation?

A

Period = 1 / Frequency

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10
Q

What direction vibrations do transverse waves have?

A

Perpdenciular to the direction the wave travels

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11
Q

Give examples of transverse waves

A

EM Waves
S Waves
Ripples and waves in water

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12
Q

What direction vibrations do longitudinal waves have?

A

Parallel to the direction the wave travels

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13
Q

Give examples of logitudinal waves

A

Sound Waves

P Waves

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14
Q

What are the compressions in longitudinal waves

A

The squashed up areas of the wave (high pressure with lots of particles)

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15
Q

What are the rarefactions in longitudinal waves?

A

The stretched out areas of the wave (lower pressure with fewer particles)

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16
Q

What is the equations for wave speed?

A 
V = F x λ
m/s = Hz x m
V = x / t
m/s = m / s
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17
Q

A wave has a speed of 0.15 m/s and a wavelength of 7.5 cm

Calculate it’s frequency

A

cm -> m
7.5/100= 0.075

v / λ = f
0.15 / 0.075 = f
2 Hz

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18
Q

What can you use to measure the speed of sound?

A

An oscilloscope

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19
Q

To measure the speed of sound what apparatus do you need?

A

A signal generator
Speaker that can generate sounds with a specific frequency
Two microphones
An oscilloscope

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20
Q

How do you setup the oscilloscope when measuring the speed of sound?

A

So the detected waves at each microphone are shown as separate waves

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21
Q

What do you do with the microphones when measuring the speed of sound?

A

Slowly move one away until the two wavess are aligned but have moved one wavelength apart

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22
Q

When measuring the speed of sound, what is one wave length equal to?

A

The distance between the microphones

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23
Q

When measuring the speed of sound, state all the measurements you need at how you get them?

A

Frequency - the frequency you set the frequency to on the speaker
Wavelength - the distance between the microphones, once they match up on the oscilloscope with one being one wavelength ahead

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24
Q

What do you use to measure the speed of water ripples?

A

A strobe light
Signal genertor
Ripple tank with a dipper

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25
Q

What do you do with the strobe light when measuring the speed of water ripples?

A

Alter the strobe lights’ frequency until it matches the ripples’ frequency

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26
Q

How do you tell the frequency of the strobe light and the ripples are the same?

A

The wave pattern on the screen will appear to freeze and stop moving

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27
Q

Why does what happens when the frequency of the strobe light and the ripples are the same happen?

A

The light lights up the waves at the same point in there cycle each time

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28
Q

When measuring the speed of water ripple what measurements must you have and how do you get them?

A

Frequency - The frequency you set tthe dipper to

Wavelength - Measure the wavelength of 10 lines apart and then find the average wavelength

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29
Q

What method do you use to find the speed of waves in solids?

A

Peak Frequency

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30
Q

When measuring the speed of waves in solids, what measurements must you take before hand?

A

The length of a metal rod

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31
Q

Tap the ___ with the ______

A

Tap the rod with the hammer

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32
Q

What does tapping the rod with a hammer give you?

A

The peak frequency

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33
Q

How many times should you repeat the peak frequency method?

A

Three times

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34
Q

How do you calculate the speed of a wave in solids?

A

Using v = fλ

λ is equal to twice the length of the rod

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35
Q

What is λ equal to when finding the speed of waves in solids?

A

Twice the length of the rod

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36
Q

λ is equal to ____ the length of the rod

A

λ is equal to twice the length of the rod

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37
Q

Describe an experiment to measure the wavelength of a water wave

A

Add water to a ripple tank with a signal generator
Set strobe light to frequency of dipper, you can tell when they’re in sync when the waves don’t appear to move
Measure the wavelength of 10 waves and then calculate and average
Times that by the frequency of the dipper to calculate wave speed

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38
Q

What can happen to waves when they meet boundaries?

A

Reflected
Absorbed
Transmitted

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39
Q

How do you remember what happens to waves when they meet boundaries?

A

R.A.T (Toby)

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40
Q

What happens when a wave us absorbed?

A

The wave transfers energy to the materials energy stores

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41
Q

What happens when a wave is transmitted?

A

The wave carries on travelling through the new material

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42
Q

What does wave transmission lead to?

A

Refraction

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43
Q

What is refraction used in?

A

Communications
Glasses
Cameras

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44
Q

What happens when a wave is reflected?

A

The wave is neither absorbed or transmitted instead it is sent back away from the second material

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45
Q

What is an example of a wave being reflected?

A

An echo

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46
Q

What is refraction?

A

Waves changing directions at a boundary

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47
Q

Waves travel at _______ speeds in materials with ______________

A

Waves travel at different speeds in materials with different densities

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48
Q

When does refraction not occur?

A

When a wave travels along the normal or when the densities of the two mediums are the same

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49
Q

The _______ the change in speed, the more a wave bends

A

The greater the change in speed, the more a wave bends

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50
Q

Compare the speed of EM waves in a vaccum to a denser material

A

EM waves travel slower in denser materials

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51
Q

What affects how much an EM wave refracts?

A

Wavelength

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52
Q

How does wavelength affect refraction?

A

The shorter the wavelegnth, the more the wave bends

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53
Q

What stays the same as the wave passes the boundary?

A

It’s frequency

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54
Q

In terms of refraction, what is the relationship between wavelength and velocity?

A

As wavelength decreases, velocity decreases

As wavelength increases, velocity increases

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55
Q

What is the name of the ray that meets the normal at the boundary?

A

The incident ray

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56
Q

What is the angle of incidence?

A

The angle between the incident ray and the normal

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57
Q

What will happen to a light wave if it passes from a less dense to a more dense medium?

A

It will move towards the normal

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58
Q

What will happen to a light wave if it passes from a more dense to a less dense medium?

A

It will move away from the normal

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59
Q

Give an example of a low density medium

A

Air

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60
Q

Give an example of a high density medium

A

Glass

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61
Q

If a wave speeds up when it passes through a medium where does it bend to?

A

Away from the normal

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62
Q

If a wave slows down when it passes through a medium where does it bend to?

A

Towards the medium

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63
Q

How does Izak remember what happens with the speed of a wave and refraction?

A

Like a graviational pull, if you go fast enough you can escape if you don’t you get pulled in

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64
Q

A light ray enters air from water at 50* to the nrmal

How does it bend relative to the normal?

A

Away from the normal as gains speed

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65
Q

What are sound waves caused by?

A

Vibrating objects

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66
Q

What are the sound vibrations passed thorugh as?

A

A series of compressions and rarefactions

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67
Q

What determines which frequencies and object can transmit?

A

Size
Shape
Structure

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68
Q

Compare the speeds of speed in the different states?

A

Fastest in solid, medium in liquid and slowest in gas

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69
Q

What doesn’t change when a wave pases from one medium to another?

A

Frequency

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70
Q

What are reflected sound waves called?

A

Echoes

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71
Q

What type of objects cause sound waves to reflect?

A

Hard and flat

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72
Q

When do you hear sound?

A

When the ear drum vibrates

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73
Q

List the path sound takes in the ear

A

Outside Ear -> Eardrum -> Ossicles -> Semicircular Canals -> Cochlea -> Brain

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74
Q

What is the role of the eardrum in the ear?

A

To vibrate the sound into the ear

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75
Q

What are the name of the tiny bones in your ear?

A

The ossicles

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76
Q

What turns the sound into the electrical signals which is then sent to the brain?

A

The cochlea

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77
Q

What is the electrical signals for sound sent along?

A

The auditory nerve

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78
Q

What determines the pitch of a sound?

A

It’s frequency

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79
Q

What determines the volume of a sound?

A

It’s amplitude

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80
Q

What limits human hearing?

A

The size and shape of the eardrum

The structure of all the parts within the ear that vibrate to transmit the sound wave

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81
Q

Describe how you hear a sound wave

A

The sound enters the ear and vibrates the ear drum, which then vibrates the ossicles then the semicircular canals and then the cochlea
The cochlea then converts the sound to electrical signals which is sent along the auditory nerve to the brain

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82
Q

What happens to ultrasound waves when they hit boundaries?

A

They get partially reflected

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83
Q

What is partial reflection?

A

When a wave crosses a medium and some of the wave is reflected off the boundary whilst some is transmitted

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84
Q

What hertz is ultrasound?

A

Any frequency higher than 20,000 Hz

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85
Q

How is ultrasound useful?

A

Medical imaging
Industrial imaging
Sonar

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86
Q

How is ultrasound used for medical imaging?

A

Ultrasound is passed through the body but bounces of certain materials
A computer processes this infomation and produces a video image

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87
Q

How is ultrasound used for industrial imaging?

A

Ultrasound is used to find flaws in objects as they will enter the material and will usually be reflected by the far side of the material
However, if there is a flaw it will be reflected sooner

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88
Q

What is sonar used for?

A

To find out the deepness of the water and to locate objects in deep water

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89
Q

A pulse of ultrasound takes 4.5 seconds to travel from a submarine to the sea bed and back again
If the speed in sea water is 1520 m/s, how far away is the submarine from the seabed?

A 
S = 2D / T
2D = S x T
2D = 6840 m
D =  3420 m
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90
Q

What is infrasound?

A

Sound with frequencies lower than 20 Hz

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91
Q

What are examples of natural uses of infrasound?

A 
Animal communication (eg. Elephants and Whales)
Natural Disasters (eg. Volcanoes, Earthquakes and Avalanches)
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92
Q

How do scientists predict natural events?

A

Because these events produce infrasound

Scientists can monitor infrasound to predict it

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93
Q

What happens when seismic waves reach a boundary between different layers of material?

A

They are absorbed or refracted

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94
Q

What type of seismic wave can travel through the Earth’s core?

A

P-waves

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95
Q

What type of seismic wave can’t travel through the Earth’s core?

A

S-waves

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96
Q

What have scientists been able to work by observing seismic waves?

A

The internal structure of the Earth

The size and material of the Earths’ inner layers

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97
Q

What type of waves are P-waves?

A

Longitudinal

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98
Q

What types of state can P-waves travel through

A

Solids and liquids

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99
Q

Compare the speed of P-waves to S-waves

A

P-waves are much faster

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100
Q

What type of waves are S-waves

A

Transverse waves

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101
Q

What types of state can S-waves travel through?

A

Solid

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102
Q

Which seismic wave is transverse?

A

S-waves

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103
Q

Which seismic wave is longitudinal?

A

P-waves

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104
Q

Which seismic wave is faster?

A

P-waves

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105
Q

How do you remember which is the fastest seismic wave?

A

Primary means earliest in time meaning it is the first to get there which means it’s the fastest

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106
Q

How do you remember which seismic wave is transverse or longitudinal?

A

S is next to T in the alphabet and S-waves are Transverse

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107
Q

How do you remember which seismic wave travels through which state of material?

A

S-waves travel through solids, S for solid

Primary do everything

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108
Q

S-waves produced at the Earth’s North Pole would not be detected at the South Pole
Suggest one conclusion you can make about the Earth’s core from the observation
Explain your answer

A

S-waves can only travel through solids

S-waves can’t travel through the core, meaning atleast a bit of the core is liquid

109
Q

What is the law of reflection?

A

Angle of incidence = Angle of reflection

110
Q

What is the angle of incidence?

A

The angle between the incoming wave and the normal

111
Q

What is the incident ray?

A

The incoming ray

112
Q

What is the angle of reflection?

A

The angle between the reflected wave and the normal

113
Q

What is the reflected ray?

A

The ray that is reflected off the boundary

114
Q

What is the normal?

A

An imaginary line that’s perpendicular to the surface at the point of incidence

115
Q

What does TIR depend on?

A

The critical angle of the material

116
Q

What is the critical angle of a material?

A

The angle at which the angle of refraction is 90* (perpendicular to the normal)

117
Q

When does TIR happen?

A

When the angle a wave hits a less dense medium is greater than the critcal angle

118
Q

What is TIR?

A

Total reflection of wave from a more dense medium to a less dense medium with no wave coming out instead it all internally reflects

119
Q

Reflection can be _______ or _____

A

Reflection can be specular or diffuse

120
Q

When does specular reflection occur?

A

When waves are reflected in a single drection by a smooth surface

121
Q

When does diffuse reflection occur?

A

When waves are reflected by a rough surface

122
Q

Why does diffuse reflection occur?

A

Because the normal is different for each incident ray meaning the reflection angle is different (angle of incidence = angle of reflection)

123
Q

Name the type of reflection that occurs when waves are reflected by a smooth mirror

A

Specular

124
Q

A light ray is incident on a mirror at an angle of 30*

What will it’s total angle be?

A 
Reflection angle = 30*
∴
∠Reflection + ∠Incidence = Total Angle
30 + 30 = 60*
60*
125
Q

When investigating refraction, why should a thin beam of light be used?

A

So you can easily trace the ray to measure the angle between the ray and the angle

126
Q

What does the colour and transparency of light depend on?

A

It’s wavelength

127
Q

What are opaque objects?

A

Objects which do not transmit light

128
Q

What do white objects do?

A

Reflect all wavelengths of light equally

129
Q

What do black objects do?

A

Absorb all wavelengths of light

130
Q

What type of objects transmit light?

A

Transparent/translucent objects

131
Q

What do colour filters do?

A

Only let through particular wavelengths

132
Q

If a red object was placed in front of a blue filter what colour would the object appear?

A

Black

133
Q

Explain why a cucumber looks green?

A

Because it reflects green light but absorbs all other wavelengths of light

134
Q

Give the two types of lens’s

A

Converging (Convex)

Diverging (Concave)

135
Q

Describe a converging lens?

A

Bulges outwards in the middle

136
Q

What does a converging lens do to light?

A

Converges it at the principal focus

137
Q

Describe a diverging lens?

A

Caves inwards

138
Q

What does a diverging len do to light?

A

Spreads it out

139
Q

What is the principal focus of a converging lens?

A

The area where the rays parallel to the axis meet

140
Q

What is the principal focus of the diverging lens?

A

The area where the rays parallel to the axis appear

141
Q

How do you find the principal focus of a diverging lens?

A

Trace them back until they all appear to meet up at a point behind the lens

142
Q

What is the focal length?

A

The distance from the centre of the lens to the principal focus

143
Q

What is the unit for principal focus?

A

F

144
Q

When is an image formed?

A

When all light rays from a certain point on an object appear to come together

145
Q

Give the two types of images?

A

Real

Virtual

146
Q

When is a real image formed?

A

When lights rays actually come together to form the image

147
Q

What type of image can be put onto a screen?

A

A real image

148
Q

What type of image is found on the eye’s retina?

A

Real

149
Q

When is a virtual image formed?

A

When light rays from the object appear to be coming from a completely different place to where they’re actually coming from

150
Q

What type of image can’t be put onto a screen?

A

Virtual

151
Q

Give an example of an object which creates virtual images?

A

A magnifying glass

152
Q

What increases the power of a lens?

A

Its curvature

153
Q

Describe the relationship between power of lens and focal length

A

The more powerful the lens, the more strongly it converges rays of light, so the shorter the focal length

154
Q

What lens has a positive power?

A

Converging

155
Q

What lens has a negative power?

A

Diverging

156
Q

How can you increase the power of a lens?

A

Change the material

Increase it’s curvature

157
Q

What is the principal focus of a converging lens?

A

The point where rays hitting the lens parallel to the axis meet

158
Q

What is the principal focus of a diverging lens?

A

The point where light rays hitting the lens parallel to the axis appear to come from

159
Q

Describe the image produced from a diverging lens

A

Virtual
Right way up
Smaller
Same side of the lens

160
Q

Briefly describe how to draw a ray diagram of a diverging lens?

A

Draw two rays, one from the object through the lens and the other parallel to the axis of the lens through the lens
Refract the line that went through the lens, that is parallel to the lens
Draw dotted line from 1F to refraced ray
The point where all three lines intersect is where the image is formed

161
Q

What affects the image produced from a converging lens

A

Its distance from the object

162
Q

Briefly describe how to draw a ray diagram of a converging lens?

A

Draw two rays, one from the object through the lens and the other parallel to the axis of the lens through the lens
Refract the line through 1F
The image will form when the refracted ray meets the ray that went straight through the lens

163
Q

How will the object appear when 2F away from a converging lens?

A 
Same size
2F away
inverted
Real
Other side of the lens
164
Q

How will the object appear when 1F-2F away from a converging lens?

A

Real
Inverted
Bigger
Beyond 2F

165
Q

How will the object appear when <1F away from a converging lens?

A

Virtual
Right way up
Bigger
Same side of the lens

166
Q

On a ray diagram, what determines whether the image is upright?

A

If its above the axis

167
Q

On a ray diagram, what determines whether the image is inverted?

A

If its below the axis

168
Q

On a ray diagram, what determines whether the image is real?

A

If the image is past the lens

169
Q

On a ray diagram, what determines whether the image is virtual?

A

If the image is before the lens

170
Q

What kind of image does a diverging lens produce?

A

Virtual

171
Q

Compare the speeds of EM waves?

A

The same in a vacuum

But different in different materials

172
Q

What do we group EM waves off?

A

Wavelength/frequency

173
Q

How many EM waves are there?

A

7

174
Q

Name all the EM waves

A 
Radiowaves
Microwaves
Infrared
Visible light
Ultraviolet
X-rays
Gamma rays
175
Q

What causes the generation of EM waves?

A

Changes in atoms and their nuclei

176
Q

What creates gamma rays?

A

Changes in an atoms nucleus

177
Q

What creates visible light?

A

Changes in an electrons energy level

178
Q

What does the higher frequency mean of a wave?

A

The more energy it transfers

179
Q

What EM wave transfers the most energy?

A

Gamma rays

180
Q

Describe the interaction between the human body and radio waves

A

No harm as the waves are transmitted fully

181
Q

Describe the interaction between the human body and microwaves

A

Some wavelengths can be absorbed, causing the heating of cells

182
Q

What can some wavelenghts of microwaves do to the body?

A

Heat the cells

183
Q

Describe the interaction between the human body and infrared

A

Mainly reflected but can be absorbed causing heating, which may cause burns if the skin gets too hot

184
Q

Describe the interaction between the human body and visible light

A

Mainly reflected but can be absorbed causing heating

185
Q

Describe the interaction between the human body and ultraviolet

A

Absorbed by the skin which can cause damages to cells and could lead to skin cancer

186
Q

Why is ultraviolet much more dangerous than IR?

A

Because it has a higher frequency meaning its more ionising

187
Q

What can UV cause to the human body?

A

Skin cancer

Eye conditions and blindness

188
Q

Describe the interaction between the human body and x-rays

A

Absorbed which can cause mutations and damage cells

189
Q

Describe the interaction between the human body and gamma rays

A

Absorbed which can cause mutations and damage cells

190
Q

Explain why gamma rays are more dangerous to humans than visible light?

A

Gamma rays are ionising so they can cause tissue damage and cancer but visible light isn’t ionising
They carry more energy than visible light, so their potential for damage is higher

191
Q

What does every object absorb and emit?

A

EM radiation

192
Q

What does the distribution and intensity of wavelengths depend on?

A

The objects temperature

193
Q

What is intensity?

A

The power per unit area

194
Q

What happens to the object as the temperature increases?

A

The intensity of every emitted wavelength increases

195
Q

Compare the intensity of different wavelengths emitted when the object is increased?

A

The shorter the wavelength the faster the intensity increases

196
Q

Describe an object with constant temperature in terms of emission and absorption

A

Absorption = Emission

197
Q

Describe an object that is heating up in terms of emission and absorption

A

Absorbing > Emitting

198
Q

Describe an object that is cooling down in terms of emission and absorption

A

Emitting > Absorbing

199
Q

Where does the Earth get most of its radiation from?

A

The Sun

200
Q

What happens to the radiation the Sun gives to the Earth?

A

Some reflected

Most absorbed

201
Q

What does the reflected radiation do to the Earth?

A

Reflect out to the Earth’s atmosphere,clouds and surface which will cause an increase in temperature

202
Q

What happens to the absorbed radiation in the clouds/atmosphere?

A

Is emitted at night causing a decrease in the temperature

203
Q

What type of surfaces are the best emitters?

A

Black

204
Q

Briefly describe how to investigate how well different surfaces emit radiation?

A

Fill identical test tubes with hot water whilst surrounding them with different types/colours of materials (eg. Black, White, Glossy and Matte paper)
Measure the temperature, the one with the greatest temperature drop is the best emitter, the one with the lowest temperature drop is the best insulator

205
Q

What will emit better: Shiny or matte surfaces?

A

Matte

206
Q

What will emit better: White or black surfaces?

A

Black

207
Q

Explain what is happening in terms of radiation and temperature when a bowl of ice cream is left on a counter in a warm room?

A

The bowl of icecream is absorbing more infrared radiation than it is radiating
This causes an increase in the temperature of the bowl of ice cream

208
Q

What are EM waves made of?

A

Oscillating electric and magnetic fields

209
Q

What make up oscillating charges?

A

Alternating currents (AC0

210
Q

What happens when charges oscillate?

A

They produce oscillating electric and magnetic fields

211
Q

The frequency of the waves produced will equal ________________

A

The frequency of the waves produced will equal the frequency of the alternating current

212
Q

What is a transmitter, when making radio waves?

A

The object in which charges oscillate to create the radio waves

213
Q

Describe how radio waves are converted into a current

A

A reciever absorbs radio waves
The energy carried by the waves transfers to the electrons in the matierla causes the electrons to oscillate, generating an alternating current

214
Q

What are radio waves mainly used for?

A

Communication and broadcasting

215
Q

What are the wavelengths of long-wave radio waves?

A

1-10km

216
Q

What is the name for when a wave bends

A

Diffraction

217
Q

Why can long-wave radio waves go halfway around the world?

A

Because they can diffract around the curved surface of the Earth

218
Q

What are the wavelengths of short-wave radio waves?

A

10-100m

219
Q

How do short-wave radio waves go across the world?

A

By being reflected by the Earth’s atmosphere

220
Q

What type of wave does bluetooth use?

A

Short-wave radio waves

221
Q

Describe the wavelength for TV and FM radio transmissions

A

Very short

222
Q

What must waves, that are used for communication to and from satellites, be able to do?

A

Easily pass through the Earth’s watery atmosphere

223
Q

Explain why signals between satellites are usually transmitted as microwaves

A

They can easily pass through the Earth’s watery atmosphere without being absorbed

224
Q

How do microwaves work?

A

The microwaves transmit a few centimeters into the food before being absorbed and transferring the energy they are carrying to the water molecules, heating up the food

225
Q

Describe the difference between microwaves in ovens and in satellites?

A

The ones with satellites must be able to pass through the atmosphere,. whereas, the microwaves in microwaves need to be absorbed by water molecules

226
Q

Give uses of microwaves

A

Communication

Microwave ovens

227
Q

What gives out infrared radiation?

A

All warm objects

228
Q

Give uses of infrared radiation?

A 
Burgular alarms
Thermal imaging
Short range communication
Cooking
Optical fibres
229
Q

What do infrared cameras do?

A

Detects IR and converts it into an electrical signal which is displayed on a screen

230
Q

How do infrared sensors work?

A

By detecting a change in infrared radiation and then sounding an alarm or a security light

231
Q

How is infrared used for cooking?

A

Infrared causes objects to get hotter meaning adding IR to food will cause it to heat up

232
Q

What are the disadvantages of using infrared to transfer information?

A

Must be a short distance

Must be in line of sight

233
Q

What are optical fibres?

A

Thin glass or plastic fibres that carry data over long distances

234
Q

What do optical fibres rely on?

A

Total Internal Reflection

235
Q

Why do optical fibres use a single wavelength?

A

To prevent dispersion which can otherwise cause some information to be lost

236
Q

Give three uses of infrared radiation

A 
Any three from:
Burgular alarms
Thermal imaging
Short range communication
Cooking
Optical fibres
237
Q

What does photography rely on?

A

Visible light

238
Q

What are uses of visible light?

A

Photography

239
Q

How does photographic film work?

A

By reacting to light to form an image

240
Q

How do digital cameras work?

A

By using image sensors to detect visible light and generate an electrical signal which is then converted into an image

241
Q

What is ultraviolet used in?

A

Fluorescent lamps
Bank notes/passports
Security pens
Sterilising water

242
Q

What is fluorescence?

A

A property of chemicals where UV radiation is absorbed and then visible light is emitted

243
Q

How is UV used to sterilise water?

A

It’s blasted onto water killing any bacteria in it

244
Q

What are x-rays used for?

A

To view the internal structure of objects and materials

245
Q

How do radiographers take x-ray images?

A

The patient is placed on a detector plate whilst x-rays are directed onto the body, the x-rays transmit through the flesh and are absorbed by denser material (eg. Bones and Metal) meaning the image will pick up areas of high x-ray amount meaning low density material (eg Flesh) and areas of low x-ray amount meaning high density material (Eg. Bones and Metal)

246
Q

What are gamma rays used for?

A

Sterilisation
Medical imaging
Cancer treatments

247
Q

How are gamma rays used in sterilisation?

A

They kill microbes

248
Q

What are the benefits of using gamma rays to steralise food?

A

No need to freeze it, cook it or preserve it some other way

249
Q

Give examples of gamma being used in medical imaging?

A

PET scans and tracers

250
Q

How are gamma rays used in cancer treatments?

A

Targeted at cancer cells to kill them

251
Q

What are the cons of using gamma radiation for cancer treatment?

A

If not aimed correctly will cause damage to healthy cells

252
Q

State two uses of ultraviolet radiation?

A 
Any two from:
Fluorescent lamps
Security pens
Detecting forged bank notes
Sterilising water
253
Q

Suggest one advantage of sterilising food with gamma rays

A

You don’t have to freeze it/cook it/preserve it to keep it fresher for longer

254
Q

What is the amplitude of a wave?

A

The displacement from the rest position to a crest or trough

255
Q

What is the wavelength of a wave?

A

The length of a full cycle of the wave

256
Q

What is the frequency of a wave?

A

The number of complete cycles per second

257
Q

What is the period of a wave?

A

The number of seconds it takes for one full cycle

258
Q

Describe the difference between transverse and longitudinal waves?

A

In longitudinal waves, the vibrations are parallel to the direction of wave travel.
In transverse waves, the vibrations are at right angles to the direction of wave travel.

259
Q

What affects an objects ability to transmit given frequencies of sound?

A

It’s size, shape and structure

260
Q

What is the frequency of ultrasound?

A

> 20,000 Hz

261
Q

What is the frequency of infrasound?

A

> 20 Hz

262
Q

What conditions are needed for total internal reflection to occur?

A

The light must be travelling from a more dense medium into a less dense medium (eg. glass to air)
The angle of incidence must be greater than the critical angle.

263
Q

Explain what happens to white light that hits a white object?

A

All of the light is reflected by the object

264
Q

True or False? Diverging lenses always produce real images?

A

False

265
Q

True or false? All EM waves are transverse?

A

True

266
Q

Give one danger of UV radiation?

A

Any one from:
Skin cancer
Cataracts
Blindness

267
Q

Give one danger of x-rays/gamma rays

A

Mutation of the genes

268
Q

Describe the average power absorption and radiation for an object of constant temperature

A

Equal absorption and radiation

269
Q

What kind of current is used to generate radio waves in an antenna?

A

Alternating current

Physics GCSE (8 decks)

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