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A level physics > Particles > Flashcards

Particles Flashcards

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Physics 101 flashcards AP® Physics flashcards
1
Q

What is an atom?

A

An electrically neutral collection of electrons, protons and neutrons. The number of electrons in an atom is equal to the number of protons.

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2
Q

What is an element?

A

A substance that cannot be broken down by chemical means into simpler substances

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3
Q

What is a nucleon?

A

A particle that makes up the nucleus - either a proton or neutron

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4
Q

What is the nucleon number?

A

The total number of nucleons in the nucleus(protons + neutrons). Sometimes known as the mass number

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5
Q

What is an ion?

A

An atom that has gained or lost one or more outer electrons leaving its charge unbalanced. They are charged either negatively or positively.

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6
Q

What is a nuclide?

A

A nuclide is the nucleus of a unique atom that is one with a specific number of protons and neutrons.

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7
Q

What is an isotope?

A

Atoms of an element with different numbers of neutrons but the same number of protons. They have similar qualities to the element.

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8
Q

What is the proton number?

A

The total number of protons present in the nucleus

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9
Q

What is the relative charge of a proton?

A

+1

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10
Q

What is the relative charge of a neutron?

A

0

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11
Q

What is the relative charge of an electron?

A

-1

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12
Q

What is the relative mass of a proton?

A

1

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13
Q

What is the relative mass of a neutron?

A

1

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14
Q

What is the relative mass of an electron?

A

0.0005

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15
Q

Which sub-atomic particle affects the element’s reactions and chemical behaviour?

A

Electrons

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16
Q

Which sub-atomic particle affects the stability of the nucleus?

A

Neutrons

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17
Q

What is the specific charge of a particle?

A

Particle’s ratio of its charge to its mass

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18
Q

What is the equation to calculate the specific charge?

A

Specific charge = charge/mass

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19
Q

What is a fundamental particle?

A

A particle that can’t be broken down into anything smaller

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20
Q

What are the units for the specific charge?

A

C/kg

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21
Q

What is the attractive force that holds the nucleus together?

A

Strong nuclear force

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22
Q

Describe the Strong nuclear force

A
  • It is an attractive force that is stronger than the electrostatic force
  • Experiments show that it has a very short range(a few femtometers( 1fm = 1*10^-15m)) and the force quickly falls beyond this distance
  • It works equally between all nucleons
  • At very small separations, the force must be repulsive or it would crush the nucleus
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23
Q

Describe the Strong Nuclear force graph

A
  • The force is repulsive for very small separations of nucleus
  • As nucleon separation increases past 0.5fm, the force becomes attractive. It reaches a maximum attractive value and then falls rapidly towards zero after ~3fm,
  • The electrostatic force extends over an infinite range
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24
Q

What type of emissions happen during radioactive decay?

A

Alpha
Beta(+ or -)
Gamma

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25
Q

How is an alpha particle similar to a helium nucleus?

A

It contains 2 protons and 2 neutrons

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26
Q

What happens when an alpha particle is emitted?

A

The proton number decreases by two, and the nucleon number decreases by 4

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27
Q

What is a beta emission?

A

A fast moving electron emitted from the nucleus

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28
Q

Which other particle is emitted when a beta particle is emitted?

A

Neutrino

It carries some energy and momentum

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29
Q

How were neutrinos discovered?

A

Scientists observed beta decay and observations showed that the energy of the particles after the beta decay was less than it was before(didn’t fit the conservation of energy principle)

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30
Q

What did Wolfgang Pauli suggest in 1930?

A

Another particle was being emitted which carried away the missing energy
the particle had to be neutral and have zero or almost zero mass, as it had never been detected

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31
Q

What are photons?

A

Packets of electromagnetic radiation

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32
Q

What does each particle have?

A

Each particle has an antiparticle with the same mass and rest energy but opposite charge

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33
Q

What happens when energy is converted into mass?

A

Equal amounts of matter and antimatter is produced

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34
Q

What is rest energy?

A

The amount of energy needed to make one of the particles and the amount of energy released if one of these particles was destroyed

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35
Q

What is annihilation?

A

This occurs when a particle and antiparticle collide producing 2 photons

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36
Q

What factor affects the photon energy?

A

Frequency

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37
Q

What is the equation for calculating photon energy?

A

E=hf or

E =hc/wavelength

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38
Q

What is produced by the annihilation of a particle and antiparticle?

A

Photons of energy

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39
Q

What is pair production?

A

This is when high energy gamma photons produce a particle and its antiparticle

40
Q

What is the speed of light?

A

3.00*10^8 m/s

41
Q

What is the antiparticle of a proton?

A

antiproton

42
Q

What is the antiparticle of an electron?

A

positron

43
Q

What is the antiparticle of a neutron?

A

antineutron

44
Q

What is the antiparticle of a neutrino?

A

antineutrino

45
Q

What is the strong nuclear force?

A

The force that keeps the nucleons in the nucleus together. It is both repulsive and attractive.

46
Q

What are the 4 fundamental forces?

A

Weak force
Gravity
Strong nuclear force
Electromagnetic force

47
Q

What particles are responsible for the electromagnetic force?

A

Virtual photons

48
Q

What is a virtual photon?

A

The exchange particle that carries the electromagnetic force between charged paticles

49
Q

Why are the photons referred to as ‘virtual’?

A

They can’t be seen directly

If intercepted, the force wouldn’t work

50
Q

What is the electromagnetic force?

A

A force that affects charged particles

51
Q

What is the weak force?

A

A force that affects all types of particles

52
Q

What particles are responsible for the strong nuclear force?

A

Gluons

53
Q

What particles are responsible for the weak nuclear force?

A

W+ and W- bosons

54
Q

Describe B- decay

A

A neutron in the nucleus can turn into a proton emitting and electron and an electron antineutrino. The reaction occurs via the weak interaction and is mediated by a W- boson

55
Q

Describe the B+ decay

A

A proton decays into a neutron emitting an electron neutrino and a positron. The reaction occurs via the weak interaction and is mediated by a W+ boson

56
Q

Describe the neutrino-neutron collisions

A

A neutron can absorb an electron neutrino, emitting a proton and an electron. The reaction occurs via the weak interaction and is mediated by a W- boson

57
Q

Describe the antineutrino-proton collisions

A

A proton can absorb an electron antineutrino, emitting a neutron and a positron. The reaction occurs via the weak interaction and is mediated by a W+ boson

58
Q

Describe electron capture

A

A proton in the nucleus can absorb an atomic electron forming a neutron and an electron antineutrino. The reaction occurs via the weak interaction and is mediated by a W+ boson

59
Q

Describe electron-proton collisions

A

An electron can collide with a proton emitting a neutron and an electron antineutrino. The reaction occurs via the weak interaction and is mediated by a W- boson

60
Q

Describe electromagnetic repulsion

A

As two electrons get close to each other, they exchange a photon as they repel

61
Q

How does the mass of the boson affect the range of the force?

A

The larger the mass of the boson, the shorter the range of the force

62
Q

What are hadrons?

A

Particles that feel the strong nuclear force

63
Q

Why are hadrons not fundamental?

A

They are made of quarks

64
Q

What are the two type of hadrons?

A

Baryons/Antibaryons

Mesons

65
Q

What is a quark?

A

A quark is any of the set of six elementary particles together which combine into various combinations to form baryons and mesons

66
Q

What are the 6 quarks?

A

Up, Down
Charmed, Strange
Top, Bottom

67
Q

What is the charge of the quarks: up, charm and top?

A

2/3

68
Q

What is the charge of the quarks: down, strange and bottom?

A

-1/3

69
Q

What type of force do hadrons decay through?

A

Weak nuclear force

70
Q

Give examples of baryons

A

Protons

Neutrons

71
Q

Which baryon is stable out of all baryons?

A

The proton

72
Q

Which particle do all baryons decay to except protons?

A

Protons

73
Q

What is the baryon number?

A

The number of baryons in an interaction that must be conserved

74
Q

What is the baryon number for baryons and antibaryons?

A 
Baryon = 1
Antibaryon = -1
75
Q

What type of force do hadrons interact through?

A

All four fundamental interacts

76
Q

What type of force do charged hadrons interact through?

A

Electromagnetic interaction

Strong Nuclear interaction

77
Q

What is formed when a neutron decays?

A

Proton + electron + Antineutrino

78
Q

What are mesons?

A

Hadrons that do not include protons in their decay products

79
Q

Give examples of mesons

A

Kaons

Pions

80
Q

What are mesons made up of?

A

1 quark

1 antiquark

81
Q

Give 2 characteristics of mesons

A
  • they are all unstable

- they have a baryon number of 0

82
Q

What are pions?

A

they are the lightest mesons

there are 3 versions: negative, positive and neutral

83
Q

What are kaons?

A
  • they are mesons which are more unstable and heavier than pions
  • they have a very short lifetime and decay into pions
84
Q

Through what type of force do meson and abryons interact?

A

Strong nuclear force

85
Q

What are leptons?

A

Fundamental particles that do not experience the strong nuclear force

86
Q

Through what type of force do leptons interact?

A

Weak interaction

87
Q

What are the different types of leptons?

A

Electrons
Muons
Tau
Neutrinos

88
Q

What are muons?

A

Heavy electrons that are unstable and decay into electrons

89
Q

Why are kaons called strange particles?

A

They are produced in 2s and they decay into pions

90
Q

What is the source of high energy particles including pions and kaons?

A

Cosmic ray showers

91
Q

What are the conservation laws in particles?

A

Charge
Baryon number
Lepton number
Strangeness

92
Q

When is strangeness conserved?

A

It is preserved during the creation of kaons but not conserved during their decay
It is also conserved through the strong and electromagnetic interaction but not through the weak interaction

93
Q

Through what type of interaction can light particles decay through?

A

Light particles cannot decay through the strong interaction but through the weak interaction

94
Q

Why is mass not necessarily conserved when particles interact or decay?

A

Mass can be converted into energy and vice versa

95
Q

Explain why there is a minimum photon energy for an interaction and what happens when there is slightly more energy

A

The photon must provide enough energy to provide for the rest mass
the extra energy will provide the particles with kinetic energy

96
Q

How can you calculate the minimum photon energy needed?

A

hf = 2E

A level physics (15 decks)

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