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A Level Physics Paper 1 > Particles > Flashcards

Particles Flashcards

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1
Q

Size of nucleus

A

1x10^-14m

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2
Q

Size of atom

A

1x10^-10m

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3
Q

How many times bigger is the atom than the nucleus

A

1000

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4
Q

Why is most of the atom empty space

A

Electrons orbit at relatively large distances compared to nucleus

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5
Q

Proton number

A

Z
Number of protons in a nucleus
Atomic number
Defines what element it is

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6
Q

Why is the electron number important

A

Tells you a lot about an atoms chemical behaviour and properties

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7
Q

Nucleon number

A

A
Number of nucleons
Mass number
Gives a good approximation of an atoms mass since electrons have negligible mass

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8
Q

Why are neutrons needed

A

Hold protons together

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9
Q

Why are protons useful

A

Identify element

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10
Q

Specific charge meaning

A

Ratio of a particles charge to mass in Coulombs per kilogram (Ckg^-1)

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11
Q

Formula for specific charge of a fundamental particle

A

Specific charge=Charge/Mass

Q=C/M

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12
Q

Why does the electron have the largest specific charge

A

Smallest mass by about 1840x

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13
Q

Why does the neutron have no specific charge

A

No charge

So not affected by fields and don’t deflect

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14
Q

Specific charge of nucleus

A

Q.nucleus/M.nucleus

(protons x 1.6x10^-19) / (nucleons x 1.67x10^-19)

Electrons ignored

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15
Q

Specific charge of an ion

A

Q.ion/M.ion

(nucleons x 1.67x10^-27) + (electrons x 9.11x10^-31)

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16
Q

What are isotopes

A

Same element, same proton and electron numbers

Different number of neutrons

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17
Q

What is isotopic data

A

The relative amounts of different isotopes of an element present in a substance

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18
Q

Name a use of one of hydrogens isotopes

A

Tritium

Used to illuminate fire exit signs without the need of electricity

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19
Q

Give an example of how isotopic data can be used

A

All living things contain carbon
% of radioactive carbon 14 pretty much the same for all living things’
Amount decreases after death as it decays to stable elements
Can calculate approximate ages of archaeological finds made of dead organic matter
By using the isotopic data to find the % of carbon left

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20
Q

Where does alpha decay occur

A

Large unstable nuclei

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21
Q

What is ejected in alpha decay

A

2 protons 2 neutrons

AKA a helium nucleus

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22
Q

What happens to the element as alpha decay occurs

A

Mass number decreases by 4

Atomic number decreases by 2

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23
Q

When does gamma decay happen

A

Nucleus has too much vibrational energy

Emitting gamma radiation

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24
Q

When does beta minus decay occur

A

Nucleus has too many neutrons for protons

Undergo Beta minus decay to improve its p:n

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25
Q

What is produced in beta minus decay

A

New element with one greater proton number
An electron emit
Electron antineutrino

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26
Q

What happens in beta minus decay

A

Neutron into proton

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27
Q

What happens to the nucleon number in beta decay

A

Nothing, stays the same
Electron is not a nucleon
Nucleon into nucleon

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28
Q

When does beta plus decay occur

A

When a nucleus has few too many neutrons to protons

Undergo to improve p:n

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29
Q

What happens in beta plus decay

A

Proton turns into a neutron

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30
Q

What is produced in beta plus decay

A

New element with one less proton
A positron emit
Electron neutrino

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31
Q

Alpha deflection

A

Small in magnetic and electric fields

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32
Q

Beta deflection

A

Larger in magnetic and electric fields

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33
Q

Gamma deflection

A

None
Pass straight through
No specific charge

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34
Q

Electron capture

A

Proton rich nuclei can capture an electron from inside the atom
Turning proton into a neutron
W+ boson from Proton
And an electron neutrino emit

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35
Q

Neutron emission

A

Unstable isotope with too many neutrons could eject a fast moving neutron

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36
Q

Proton emission

A

Unstable isotope with too few neutrons ejects a fast moving proton

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37
Q

Energy mass equivalency

A

E=mc^2
Mass and energy are interchangeable
Mass converted into energy in the right circumstance

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38
Q

Explain E=mc^2 variables

A

Energy in Joules
Mass in kg
Speed of light

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39
Q

Pro vs con for energy mass equivalency

A

Incredibly difficult to initiate

Potential to release insane amounts of energy

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40
Q

eV

A

Electron volt

Kinetic energy acquired by an electron when accelerated by a potential of 1 volt

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41
Q

J to eV

A

Divide by 1.6 x 10^-19

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42
Q

eV to J

A

x by 1.6 x 10^-19

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43
Q

Why is it hard to convert mass to energy

A

Can only be done using antimatter

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44
Q

Antiparticle

A

Every particle has an associated antiparticle with the same mass but an equal and opposite charge

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45
Q

Is the neutron the same as the anti-neutron

A

No

Other quantum properties like quantum spin differ

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46
Q

Annihilation

A

When a particles mass is converted into energy if it meets its corresponding antiparticle
Particle and antiparticle cease to exist
Producing two photons
To conserve momentum

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47
Q

Energy of the radiation in annihilation

A

Total energy of particle and antiparticle
Rest energies plus kinetic energies
E=mc^2 and E=0.5mv^2

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48
Q

Why are two photons produced in annihilation

A

To conserve momentum

Cannot conserve momentum with 1

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49
Q

Explain momentum change in annihilation

A

Particle + antiparticle = 0 momentum

2 photons produced, travelling in opposite directions means momentum after is also zero

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50
Q

Issue with annihilation

A

Produces lots of energy
Antimatter doesn’t occur naturally and can only be Created in particle accelerators
Currently the energy needed to store antimatter is far higher than the energy that can be produced

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51
Q

Why must particles and antiparticles be stored in magnetic fields

A

As soon as they meet they annihilate

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52
Q

Pair production

A

Very high energy photon of EM radiation ceases to exist, creating a particle and an associated antiparticle pain in its place

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53
Q

What is the excess energy used for in pair production

A

Kinetic energy of the particles

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54
Q

How does momentum change in pair production

A

Final momenta have equal and opposite vertical components

These cancel and the momentum remains unchanged

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55
Q

When can pair production occur

A

Photon energy >= mass energy of particle, antiparticle pair

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56
Q

What region are photons that spontaneously produce a particle antiparticle pair in

A

Gamma region of EM spectrum

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57
Q

When were antiprotons first created and discovered

A

1955
High energy protons collided with stationary protons
Creating protons and antiprotons

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58
Q

Why was the Higgs boson created so long after it was predicted to exist

A

Predicted in 1964
Proved in 2012 at CERN
It is the heaviest particle of the standard model
Particle collisions didn’t have enough energy to be greater than the Higgs bosons mass energy until 2012

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59
Q

What was the problem with initial beta decay interaction theories

A

Didn’t account for electron neutrino or electron antineutrino
When a neutron turned into a proton, the difference in mass energy created the beta particle
But when its kinetic energy was measured it was always less than that available
Must be another particle, no charge, low mass that shares the kinetic energy with beta particle

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60
Q

Explain the graph to alter beta decay theories

A

X=Kinetic energy of beta particles in MeV
Y=Number of beta particles
Curve going through origin and hitting X again before 0.6MeV
Steep initially, some beta had a small kinetic energy
Peaks soon, with many having a smallish kinetic energy
Slow decrease, a few having large kinetic energy
Not a single beta particle had 0.6MeV
Rest must be going to the electron antineutrino

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61
Q

Why was it hard to detect the antineutrino in beta decay

A

Very low mass
No charge
Observed in 1956

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62
Q

Neutrino abundance fact

A

Probably the most abundant particle in universe
Billion times more neutrinos than either protons or neutrons
Each second about 600 trillion pass through every square meter of earths surface

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63
Q

4 types of fundamental forces that act between particles

A

Strong
Weak
Electromagnetic
Gravity

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64
Q

What does the strong forces act on

A

All hadrons and quarks

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65
Q

Range of strong nuclear force

A

0-0.5fm is repulsive
0.5-3fm is attractive

Where fm = 10-¹⁵m

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66
Q

What is the strong force

A

Fundamental force
That acts on all hadrons and quarks
And holds nucleons in the nucleus together

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67
Q

What is the weak force

A

Fundamental force
That acts on quarks and leptons
Causing particles to decay
(Radioactive decay usually beta +/-)

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68
Q

What does the weak force act on

A

Quarks and leptons

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69
Q

Range of weak force

A

10-¹⁸m

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70
Q

What is the electromagnetic force

A

A fundamental force
Acting on all charges particles
Holding molecules and atoms together
Creating everyday forces

71
Q

Examples of electromagnetic force

A

Tension
Drag
Push
Pull

Means friction and reaction forces can occur

72
Q

Range of electromagnetic force

A

Infinite

73
Q

Range of gravitational force

A

Infinite

74
Q

What is the gravitational force

A

Fundamental force
Acting on all particles
Incredibly weak on a small scale so negligible in particle topic

75
Q

What does the electromagnetic force act on

A

All charged particles

76
Q

What does the gravitational force act on

A

All particles

77
Q

2 forced acting on protons on nucleus

A

Electromagnetic between protons and protons trying to push them apart (replusion)
Strong force between protons and neutrons trying to pull them together (attractive)

78
Q

Forces inside a hydrogen nucleus

A

No strong nuclear force
No electromagnetic force
No forces act between nucleons since only 1 proton

79
Q

What if a nucleus was just protons

A

Electromagnetic force&raquo_space;> Strong nuclear force

Would explode

80
Q

Why do we have neutrons

A

Electromagnetic force&raquo_space;> Strong nuclear force
Must be a neutral hadron so as to not add to EM
But contribute to SF
Increase the SF so SF=EM

81
Q

How does beta minus decay alter forces in nucleus

A

No change to SF since still same number of hadrons
Increases EM since 1 more proton
Reduces difference between the two
So more stable nucleus

82
Q

How does beta plus decay alter the forces in the nucleus

A

No change to SF since still same number of hadrons
Decreases EM since 1 less proton
Reduces difference between the two
So more stable nucleus

83
Q

How many particles do I need to know about

A

12 (19 Inc antiparticles)

3 (6) Quarks
4 (8) Leptons
5 Bosons / exchange particles

84
Q

List the quarks to know

A

Up
Down
Strange

Anti up
Anti down
Anti strange

85
Q

What leptons do I need to know

A

Electron
Electron neutrino
Muon
Muon neutrino

Anti electron
Electron antineutrino
Anti Muon
Muon antineutrino

86
Q

What exchange particles do I have no know

A 
W boson
Z boson
Photon
Gluon
Higgs boson
87
Q

What is a protons quark composition

A

uud

2/3 + 2/3 - 1/3 = +1

88
Q

What is a neutrons quark composition

A

udd

2/3 - 1/3 -1/3 = 0

89
Q

What is an antiprotons quark composition

A

uud

-2/3 -2/3 + 1/3 = -1

90
Q

What is an antineutrons quark composition

A

udd

-2/3 + 1/3 + 1/3 = 0

91
Q

How are muons produced

A

Particle accelerators

High energy cosmic ray showers

92
Q

What are leptons

A

Fundamental particles involved in weak interactions (decays)

93
Q

Why is the muon/antimuon different to electron/positron

A

Heavy electron/positron

Around 200 times more massive

94
Q

What are hadrons

A

Particles composed of quarks and involved in strong interactions
Baryons and mesons

95
Q

Important to remember about quarks existance

A

Quarks cannot exist individually

Must exist in pairs (mesons) or triplets (baryons)

96
Q

Like charges can … a … to … eachother

A

Exchange
Photon
Repel

97
Q

Opposite charges can … a … to … eachother

A

Exchange
Photon
Attract

98
Q

Neutrino vs neutron

A

Neutrino is a fundamental particle whereas neutron is made of quarks

99
Q

Gluon vs pion

A

Both exchange particles for strong force

Gluons act as exchange particles between quarks
Pions act as exchange particles between hadrons

Gluons hold quarks together inside hadrons
Pions hold hadrons together

100
Q

What are the exchange particles associated with each type of force

A 
Gravity = Graviton (don't need to know)
Strong = Gluon/pion
Electromagnetic = Photon
Weak = Z/W boson
101
Q

Difference between the exchange particles of strong force or electromagnetic force and weak

A

Z and W bosons both have mass but gluons and photons do not

102
Q

Which bosons have mass

A

W+
W-
Z⁰

103
Q

Which bosons have charge

A

W-

W+

104
Q

Exchange particles in strong force interactions between quarks

A

Gluons

105
Q

Exchange particles in strong force interactions between hadrons

A

Exchange pions

106
Q

What is the higgs boson

A

Not an exchange particle

Creates a higgs field that gives mass to particles

107
Q

What is conserved in all interactions/collisions

A 
Total momentum
Total energy
Kinetic energy (if elastic)
Charge
Baryon number
Lepton number
Strangeness (in strong interactions)
108
Q

Baryon number of pions and kaons

A

Mesons are not baryons so it’s 0

E.g 1/3 + - 1/3 = 0

109
Q

What are mesons made of

A

1 quark and 1 antiquark

110
Q

What are baryons made of

A

3 quarks or 3 antiquarks

111
Q

Strangeness of a particle with 2 strange quarks

A

-2

112
Q

Strangeness of a particle with 3 anti strange particles

A

+3

113
Q

Pions

A

Mesons with strangeness of 0

114
Q

Kaons

A

Mesons with strangeness

115
Q

Quark composition of pi+

A

_
ud

Overall +1

116
Q

Quark composition of pi⁰

A

uu dd ss

Charge is 0

117
Q

Quark composition of pi-

A

_
ud

Charge is -1

118
Q

Kaon production and decay

A

Produced in cosmic ray showers
And particle accelerators
By strong interaction

Decay by weak interaction into pions

119
Q

Quark composition of K+

A

śu

Overall charge of +1

120
Q

Quark composition of K⁰

A

_
sd

Overall charge of 0

121
Q

Quark composition of anti K⁰

A

_
sd

Overall charge of 0

122
Q

Quark composition of K-

A

_
su

Overall charge of -1

122
Q

Quark composition of K-

A

_
su

Overall charge of

122
Q

Quark composition of K-

A

_
su

Overall charge of

123
Q

Quark composition of K-

A

_
su

Overall charge of -1

124
Q

What do you do if you have a mixture of leptons

A

Separate into Le and Lu

Lepton electron and lepton muon

125
Q

Electron Le and Lu

A

Le=+1

Lu=0

126
Q

Electron neutrino Le and Lu

A

Le=+1

Lu=0

127
Q

Anti electron/positron Le and Lu

A

Le=-1

Lu=0

128
Q

Anti electron neutrino Le and Lu

A

Le=-1

Lu=0

129
Q

Muon Le and Lu

A

Le=0

Lu=+1

130
Q

Muon neutrino Le and Lu

A

Le=0

Lu=+1

131
Q

Anti muon Le and Lu

A

Le=0

Lu=-1

132
Q

Anti muon neutrino Le and Lu

A

Le=0

Lu=-1

133
Q

When do you separate lepton number

A

When there’s electrons and muons
Le
Lu

134
Q

Most stable lepton

A

Electron

Muons are short lived and quickly decay into electrons

135
Q

Most stable baryon

A

Protons

Isolated neutrons will eventually decay into protons

136
Q

Muon decay

A

u- —> e- + vu + ve

Muon (negative) into an electron, muon neutrino and an anti electron neutrino

137
Q

Order for normal interactions without electrons and muons together

A

Q
B
L
S

138
Q

Neutrino

A

Fundamental particle
No charge
Very small or zero mass
Interacts with other matter very weakly

139
Q

Equation for feynman diagram at each junction for electron electron interaction

A

e2- —> e1- + gamma

e1- + gamma —> e2-

140
Q

What goes on the y axis in feynman diagrams

A

Time

141
Q

Exchange particles in beta minus decay

A

W- from neutron

Goes into beta- and anti ve in feynman diagram

142
Q

Equations on the left junction for beta minus decay

A

n —> p + W-

d —> u + W-

143
Q

How are particles and exchange particles represented on feynman diagrams

A

Straight lines for particles

Wiggly lines for exchange particles

144
Q

Equation at right junction of beta minus decay

A

W- —> B- + anti ve

Same for quark composition feynman diagram

145
Q

What exchange particles is involved in beta plus decay

A

W+

Comes from proton and into positron and electron neutrino

146
Q

Equation on left junction for beta plus decay

A

p —> n + W+

u —> d + W+

147
Q

Equation on right for beta plus decay

A

W+ —> B+ + ve

Same for quark composition diagram

148
Q

Electron capture equation

A

p + e- —> n + ve

W+ boson as exchange particles from proton into electron

149
Q

Exchange particles in electron proton collision

A

W- boson from electron to proton

150
Q

Why is a colorimeter better than benedicts

A

Benedicts is only semi quantititive so only gives an idea of how much sugar is present by giving you a range of colours
Doesn’t tell you the concentration of sugar in the solution
Colorimeter is quantititive test so gives you a light intensity reading for light passing through the solution

151
Q

Test for starch

A

Iodine

2 drops of potassium iodide solution to sample
A blue black colour indicates the presence of starch

152
Q

What is the standard model

A

Table
With types of quarks
Types of leptons
And bosons (exchange particles)

153
Q

Why do you get electron neutrino in beta plus decay

A

Left sides lepton number is zero
Without, right would be negative (antiparticle means -1 L)
So need an electron neutrino to add same amount of charge to get right hand side to zero

154
Q

Why is an anti electron neutrino produced in beta minus decay

A

Left sides lepton number is zero
Without, right would be positive (+1 L)
So need an anti electron neutrino to decrease same amount of charge to get right hand side to zero

155
Q

Strong nuclear force vs electromagnetic for range

A

Electromagnetic plateaus and never reaches 0 so range is infinite
SNF soon reaches zero after a few fm

156
Q

Strange particle vs non strange particle

A

Strange has strangeness and a strange quark
Strange has a longer half life than expected
Strange decay by weak interaction

157
Q

What will everything eventually decay into

A

Proton

158
Q

What an an antiparticle

A

All properties are opposite

Except mass which is the same

159
Q

Explain what is meant by electron capture

A 
An atomic/shell/orbital electron
Interacts with a proton
In the nucleus
By weak interaction
Forming a neutron
u>>>>d
Neutrino released
160
Q

State what roles exchange particles can play in an interaction

A

Transfer energy
Transfer momentum
Transfer force
Can sometimes transfer charge

161
Q

What are exchange particles

A

Particles that are transferred between particls when a force acts between them

162
Q

Most stable baryon

A

Proton

Uud

163
Q

Most stable meson

A

Pion

Kaon decay into pions

164
Q

Why isn’t it possible for a free proton to decay into a neutron without input of energy

A

Rest energy of neutron greater than rest energy of proton

So energy must be supplied

165
Q

Scientists believe there is more matter than antimatter in the universe
Why is this surprising and what does it suggest about the interactions of particles in the early universe

A

Suprising since matter and antimatter must be created in equal amounts to conserve Barton, lepton and change number

Suggesting that the formation of the universe did not follow conservation laws

166
Q

What determines the range of the force

A

Size of exchange particles
Heavier means shorter range
E.g W boson is very heavy, so short lived and hard to detect
But a virtual photon has no mass, so em has infinite range and can be detected

167
Q

Z vs W boson

A

W has mass Z has mass

W charged Z no charge

168
Q

Rest mass and charge of a photon

A

0

169
Q

Describe what happens to the quarks in a neutron when beta minus decay occurs

A

Down into up
Via weak interaction
W- boson

170
Q

How can the momentum and energy of a gamma Ray be determined from the properties of the electron positron pair

A

Both conserved in particle interaction

Total momentum before and total energy before is equal to the momentum of gamma Ray before

171
Q

Energy after pair production

A

Rest energy + kinetic energy

172
Q

Why can’t a kaon be sś

A

Strangeness would be zero
So would actually be a pion
Since kaons have a strangeness

A Level Physics Paper 1 (8 decks)

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