Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

A LEVEL - Physics > Section 1 - Particles > Flashcards

Section 1 - Particles Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

Describe the nuclear model of an atom.

A
  • Central nucleus containing protons and neutrons

* Electrons orbit the nucleus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are nucleons?

A

Protons and neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the collective name for protons and neutrons?

A

Nucleons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How the charge and mass of protons, neutrons and electrons usually given?

A
  • It can be given and coulombs and kilograms, but the numbers are very small (e.g. +1.60 x 10^-19 coulombs)
  • Therefore, the RELATIVE charges and masses are used instead sometimes (e.g. +1)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Do you need to learn the charges and masses of protons, electrons and neutrons?

A

No, they are given to you in the exam. However, you need to know the RELATIVE charges and masses.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the unit for charge of particles?

A

Coulombs (C)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the unit for the mass of a particle?

A

Kilograms (kg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the charge of protons, neutrons and electrons?

A
  • Protons = + 1.60 x 10^-19 C
  • Neutrons = 0 C
  • Electrons = - 1.60 x 10^-19 C
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the mass of protons, neutrons and electrons?

A
  • Protons = 1.67 x 10^-27 kg
  • Neutrons = 1.67 x 10^-27 kg
  • Electrons = 9.11 x 10^-31 kg
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the relative charge of protons, neutrons and electrons?

A
  • Protons = +1
  • Neutrons = 0
  • Electrons = -1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the relative mass of protons, neutrons and electrons?

A
  • Protons = 1
  • Neutrons = 1
  • Electrons = 0.0005
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the symbol for proton number?

A

Z

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the symbol Z?

A

The proton number

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does the proton number determine?

A

Which element the atom is of.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What does the electron number determine?

A

The chemical behaviour and reactions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is another name for the mass number?

A

The nucleon number.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the nucleon number?

A

The number of protons and neutrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the symbol for nucleon number?

A

A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the symbol A?

A

The nucleon number.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is an atom’s relative atomic mass equal to?

A

The nucleon number (the number of protons and neutrons).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are isotopes?

A

Atoms with the same number of protons but different number of neutrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the 3 isotopes of hydrogen and what is their composition?

A
  • Hydrogen - 1 proton, 0 neutrons
  • Deuterium - 1 proton, 1 neutron
  • Tritium - 1 proton, 2 neutrons
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does changing the number of neutrons in atom affect it?

A
  • Doesn’t affect the chemical properties

* Affects the stability of the nucleus -> May cause decay

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How can isotopes be used to find out how old a sample is?

A

The amount of radioactive carbon-14 left in a sample can be used to calculate the approximate age (if the object is made of organic matter).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Why can carbon-14 be used to find out how old stuff is?

A
  • All living things contain the same percentage of carbon-14 taken in from the atmosphere
  • After they die, the amount of carbon-14 decreases with time as it decays
  • Looking at a sample, the amount of carbon-14 tells you how old it is
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is specific charge?

A

The ratio of the charge of a particle to its mass.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the unit for specific charge?

A

Coulombs per kilogram (C/kg)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the equation for specific charge?

A

Specific charge = Charge / Mass

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What would happen in the nucleus if the strong attraction didn’t exist?

A

Electrostatic repulsion would overcome gravity and the particles would fly apart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What does the strong nuclear force do?

A

Binds nucleons together in the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are the properties of the strong nuclear force?

A
  • Stronger than the electrostatic force
  • Very short range - only a few femtometres (the size of a nucleus)
  • Works equally between all nucleons (i.e. The force is the same between proton-proton, neutron-neutron, neutron-proton)
  • At very short separations, it is repulsive. At larger separations, it is attractive.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Describe how the strong nuclear force changes with separation.

A
  • At very small separations (below 0.5fm), it is repulsive
  • At the “equilibrium distance” (about 0.5fm), no force is exerted
  • At larger separations (over 0.5fm), it is attractive. It reaches a maximum attractive value and then falls rapidly. It is almost zero past 3fm.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Why must the strong nuclear force be repulsive at very small separations?

A

Otherwise it would crush the nucleus to a point.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

In what nuclei does alpha emission happen and why?

A
  • Very big nuclei, like uranium and radium.

* The nuclei are too massive for the strong nuclear force to keep them stable.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What happens to proton number and nucleon number when alpha decay happens?

A
  • Proton number decreases by 2

* Nucleon number decreases by 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Compare when alpha and beta emission happen.

A
  • Alpha emission -> In very large nuclei

* Beta emission -> In neutron-rich nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the range of alpha particles and how can this be observed?

A
  • Very short
  • By looking at tracks left by alpha particles in a cloud chamber or by using a Geiger counter to observe how count rate drops with distance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is beta-minus decay?

A

The changing of a neutron into a proton, while emitting an electron and antineutrino from the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

In what nuclei does beta-minus decay happen and why?

A
  • Neutron-rich nuclei

* Having many more neutrons than protons in the nucleus makes it unstable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What happens to proton number and nucleon number when beta-minus decay happens?

A
  • Proton number increases by 1

* Nucleon number stays the same

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the range of beta particles?

A

Much greater than alpha particles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What does the antineutrino in beta decay do?

A

Carries away some energy and momentum.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Describe how the first hypothesis about neutrinos was created.

A
  • Scientists at first thought only electrons were emitted during beta decay.
  • However, it was observed that the energy after beta decay was less than before beta decay.
  • This led to the idea that another particle was emitted too, which carried the missing energy.
  • It would have to have no charge and almost zero mass.
  • This was later found to be the neutrino.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Remember to revise the graph of the strong nuclear force.

A

Pg 4 of the revision guide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is the order of the EM spectrum by increasing frequency?

A
  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • UV
  • X-rays
  • Gamma rays
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What equation links frequency and wavelength of EM waves?

A

Frequency = Speed of Light in Vacuum / Wavelength

f = c / lambda

(NOTE: This is a variation of the “v = f x lambda” equation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is the speed of light in a vacuum?

A

3.00 x 10^8 m/s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What are photons?

A

Packets of electromagnetic radiation.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

When are EM waves emitted?

A

When a charged particle loses energy. This can be when:
• A fast-moving electron is stopped
• An electron in a shell moves to a shell of lower energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Describe the structure of an EM wave.

A

A magnetic wave and an electric wave at 90* to each other and to the direction of travel. They are in phase.

(See diagram pg 8 of textbook)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What is the equation for the energy of a photon?

A

Energy (J) = Planck’s constant (Js) x Frequency (Hz)

E = h x f

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What is the wavelength of visible light?

A

400-700nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What is Planck’s constant?

A

6.63 x 10^-34 Js

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What is the equation for the power of a laser?

A

Power = No. of photons passing a point per second x Photon energy

P = n x E = n x h x f

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What units may be used to give the energy of a photon?

A

Joules (J) or Mega electronvolts (MeV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

How many joules is one MeV?

A

1.60 x 10^-13 J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What equation can be used to calculate the rest energy of a particle?

A

E = m x c^2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

What is an electronvolt?

A

The energy that one electron would gain when accelerated through a potential difference of 1 volt.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

How do you convert from joules to MeV?

A

Divide by 1.6 x 10^-13.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What is an antiparticle?

A

A corresponding particle to a particle with the same mass and rest energy, but opposite charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is the general unit for rest energy?

A

MeV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Describe simply the idea of energy and mass equivalence.

A

Energy can turn into mass and mass can turn into energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What is the rest energy of a particle?

A

The “energy equivalent” of the particle’s mass.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What happens in terms of mass production when energy is converted into mass?

A

Equal amounts of matter and antimatter are produced.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What is the antiparticle of the proton?

A

Antiproton

66
Q

What is the antiparticle of the neutron?

A

Antineutron

67
Q

What is the antiparticle of the electron?

A

Positron

68
Q

What is the antiparticle of the neutrino?

A

Antineutrino

69
Q

What is beta-plus decay?

A
  • When a proton turns into a neutron, and a positron and neutrino are emitted.
  • It is not a natural form of decay and it only happens in experiments.
70
Q

What is pair production?

A

When a photon turns into a particle and antiparticle.

71
Q

When can pair production happen?

A

When the photon has enough energy to produce the mass of the particle and antiparticle.

72
Q

Which photons have enough energy to produce mass through pair production?

A

Gamma ray photons.

73
Q

Where does pair production usually happen and why?

A

Near the nucleus, which helps conserve momentum.

74
Q

What are the most common particles produced by pair production and why?

A

Electron-positron pairs because they have low mass.

75
Q

The minimum energy of a photon in pair production is equal to…

A

…the total rest energy of the particles produced.

76
Q

What is the symbol for rest energy?

A

E0

77
Q

What is the equation for the minimum energy of a photon during pair production?

A

Minimum energy of photon = 2 x Rest energy of each particle produced

Emin = 2E0
or
h x fmin = 2E0

78
Q

What happens when a particle and antiparticle meet?

A
  • Annihilation

* All of the mass of the particles is converted back to energy.

79
Q

The total minimum energy of both photons produced in annihilation is equal to…

A

… the total of the minimum energies of the particle and antiparticle.

80
Q

What is the energy for the minimum energy of a photon produced in annihilation?

A

Total minimum energy of both photons = Total minimum energy of particle and antiparticle

2Emin = 2E0 …and so… Emin = E0

81
Q

Is the interaction between two distant objects instantaneous?

A

No - this is explained by the need for exchange particles, which cause forces.

82
Q

What is the collective name for exchange particles?

A

Gauge bosons

83
Q

What are the four fundamental forces?

A
  • Weak nuclear force
  • Strong nuclear force
  • Electromagnetic force
  • Gravity
84
Q

What is the exchange particle of electromagnetic force?

A

Virtual photon (gamma symbol)

85
Q

What particles are affected by the electromagnetic force?

A

Charged particles

86
Q

What is the exchange particle of the weak nuclear force?

A

W+, W- and Z0 bosons

87
Q

What particles are affected by the weak nuclear force?

A

All types

88
Q

What is the exchange particle of the strong nuclear force?

A
  • Gluons exchanged between quarks

* Pions exchanged between nucleons

89
Q

What particles are affected by the strong nuclear force?

A

Hadrons only

90
Q

What is the exchange particle of gravity?

A

Graviton

91
Q

What particles are affected by gravity?

A

All types

92
Q

Is particle physics concerned with gravity?

A

Not really - it is usually ignored because it is very feeble unless large masses are involved.

93
Q

What is the mass of a W boson?

A

About 100 times that of a proton.

94
Q

Compare and explain the ranges of a W boson and a photon.

A
  • W boson - Very short range because it has a large mass. This means it requires a lot of energy to create and can’t travel very far.
  • Photon - Infinite range because it has zero mass.
95
Q

What are the different types of line on a Feynman diagram used to represent?

A
  • Gauge bosons (exchange particles) - wiggly lines

* Other particles - straight lines

96
Q

What are the rules for drawing Feynman diagrams?

A
  • Incoming particles start at the bottom and move upwards
  • Baryons and leptons can’t cross from one side to the other
  • Make sure charges on both sides balance
  • A W- particle going to the left has the same effect as a W+ parcial going to the right
97
Q

What exchange particle is involved in two electrons repelling each other?

A

Virtual (gamma) photon

98
Q

What are electron capture and electron-proton collisions?

A
  • Electron capture is when a proton and electron are attracted by the electromagnetic interaction and a W+ boson goes from the proton to the electron, causing a neutron and neutrino to be formed.
  • Electron collision is when the proton and electron collide. The same products are formed but a W- boson travels from the electron to the proton instead.
99
Q

What is the difference between electron capture and electron-proton collision?

A
  • In electron capture, a W+ boson travels from the proton to the electron.
  • In electron-proton collisions, a W- travels from the electron to the proton.
100
Q

What is the particle equation for beta-minus decay?

A

Neutron -> Proton + Electron + Antineutrino

101
Q

What is the particle equation for beta-plus decay?

A

Proton -> Neutron + Positron + Neutrino

102
Q

Why is an antineutrino produced in beta-minus decay, while a neutrino is produced in beta-plus decay?

A

To conserve lepton number.

103
Q

What is a virtual particle?

A

Particles which exist for only a very short time and cannot be detected.

104
Q

Remember to learn specific Feynman diagrams.

A

Pg 9

105
Q

Practice drawing our a spider diagram of the different types of particles.

A

Do it!

106
Q

What are hadrons?

A

Particles that feel the strong nuclear force. They are not fundamental.

107
Q

What are hadrons made of?

A

Quarks

108
Q

Are hadrons fundamental particles?

A

No, they are made of quarks.

109
Q

What are the two types of hadrons?

A
  • Baryons

* Mesons

110
Q

What is the difference between baryons and mesons?

A
  • Baryons - Made of 3 quarks and decay into a proton directly or indirectly
  • Mesons - Made of a quark and antiquark and do not decay into a proton
111
Q

Name some baryons.

A
  • Protons
  • Neutrons
  • Other particles (e.g. Sigmas)
112
Q

What is the only stable baryon?

A

Proton - this means all baryons will decay in sequence and eventually form a proton.

113
Q

Are antibaryons found in ordinary matter?

A

No, because they annihilate with baryons.

114
Q

What values are particles given in baryon number conservation?

A
  • Baryons = +1
  • Antibaryons = -1
  • Other particles = 0
115
Q

What are some examples of antibaryons?

A
  • Antiprotons

* Antineutrons

116
Q

Why does beta decay happen?

A

Neutrons are not stable baryons, but protons are, so a neutron will decay into a proton.

117
Q

Are mesons stable?

A

No

118
Q

What are the different types of meson?

A

Pions and kaons

119
Q

What is another name for a pion?

A

Pi-meson

120
Q

What is another name for a kaon?

A

K-meson

121
Q

What is the difference between pions and kaons?

A
  • Pions - Lighter, less unstable, not strange

* Kaons - Heavier, more unstable, strange

122
Q

What happens to kaons?

A

They decay into pions.

123
Q

How were pions and kaons discovered?

A

In cosmic rays.

124
Q

How do mesons interact with baryons?

A

Through the strong force.

125
Q

What are the general rules for determining the type of interaction in a reaction?

A
  • If any leptons involved at all -> Weak interaction
  • If strangeness isn’t conserved -> Weak interaction
  • All others -> Strong interaction
126
Q

What are leptons?

A

Particles that do not feel the strong interaction. They are fundamental.

127
Q

What are the different leptons?

A
  • Electrons
  • Muons
  • Neutrinos
  • Tau
128
Q

What happens to muons?

A

The eventually decay into electrons. This is because muons are unstable.

129
Q

What can muons be described as?

A

Heavy electrons.

130
Q

What is the mass and charge of neutrinos?

A
  • Mass - Almost zero

* Charge - Zero

131
Q

How does lepton conservation work?

A
  • There are 3 generations of lepton number - electron, muon and tau
  • Each lepton number must be conserved separately
  • Each normal lepton and its respective neutrino is given a lepton number of +1
  • Each anti-lepton and its respective antineutrino is given a lepton number of -1
132
Q

What are the symbols for each lepton number?

A
  • Electron lepton number = Le
  • Muon lepton number = Lmuon
  • Tau lepton number = Lt
133
Q

What are antiparticles of hadrons made from?

A

Antiquarks

134
Q

How do strange particles (e.g. kaons) interact?

A
  • Created by the strong interaction

* Decay via the weak interaction

135
Q

Strange particles are always produced in pairs (e.g. K+ and K-). Why?

A

The strangeness cancels out to become 0, so that strangeness is conserved. Therefore, the reaction is a strong interaction.

136
Q

What are the types of quark?

A
  • Up
  • Down
  • Strange
137
Q

What is the charge of an up quark?

A

+2/3

138
Q

What is the charge of a down quark?

A

-1/3

139
Q

What is the charge of a strange quark?

A

-1/3

140
Q

What is the charge of an anti-up antiquark?

A

-2/3

141
Q

What is the charge of an anti-down antiquark?

A

+1/3

142
Q

What is the charge of an anti-strange antiquark?

A

+1/3

143
Q

What is the strangeness of a strange quark?

A

-1

144
Q

What is the strangeness of an anti-strange antiquark?

A

+1

145
Q

What is unusual about strangeness?

A
  • It is not ALWAYS conserved

* Strange quarks are given a strangeness of -1 and anti-strange antiquarks are given a strangeness of +1

146
Q

What quarks make up a proton?

A

uud

147
Q

What quarks make up an antiproton?

A

anti-u, anti-u, anti-d

148
Q

What quarks make up a neutron?

A

udd

149
Q

What quarks make up an antineutron?

A

anti-u, anti-d, anti-d

150
Q

What are baryons made of?

A

3 quarks

151
Q

What are mesons made of?

A

A quark and an antiquark

152
Q

What is the antiparticle of a pi-plus meson?

A

A pi-minus meson.

153
Q

Remember to revise the diagram on mesons.

A

Pg 14 of the revision guide

154
Q

What is a weak interaction in terms of quarks?

A

A weak interaction is something that changes the quark type (e.g. A neutron (udd) turning into a proton (uud))

155
Q

What properties are conserved in an interaction?

A
  • Charge
  • Baryon number
  • Strangeness (only in strong interactions)
  • Lepton number (all 3 generations separately)
156
Q

Can a quark exist on its own?

A

No.

157
Q

What is quark confinement?

A

The idea that quarks cannot exist not their own.

158
Q

Through which interaction do hadrons tend to decay?

A

Weak

159
Q

Describe the mass, range and charge of a W boson.

A
  • Non-zero rest mass
  • 0.001fm range
  • Can be positively or negatively charged
160
Q

What are the quarks in a K0 meson?

A
  • Anti-s

* d

161
Q

What are the quarks in an anti-K0 meson?

A
  • s

* Anti-d

A LEVEL - Physics (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions