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AQA A-Level Physics > Particles 1 > Flashcards

Particles 1 Flashcards

1
Q

How big is a nucleus?

A

approx diameter: 10^-14m/10^-15m

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2
Q

How big is an atom?

A

approx diameter: 10^-10m

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3
Q

Define a nucleon

A

A constituent particle of a nucleus: a proton or neutron

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4
Q

Define a nuclide

A

A specific isotope of a nucleus

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5
Q

Give an example of a nuclide

A

C-14 and C-12 are isotopes of carbon but they are different nuclides

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6
Q

Define an isotope

A

a nucleus with the same number of protons but a differing number of neutrons

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7
Q

What is meant by specific charge?

A

the charge per unit mass

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8
Q

How do you calculate specific charge?

A

specific charge = (net charge) / (total mass)

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9
Q

What is an ion?

A

a charged atom

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10
Q

a Ca
b
has how many protons, neutrons and electrons?

A

protons: b
neutrons: a - b
electrons: b

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11
Q

What is the nucleon number?

A

the number of protons and neutrons in the atom

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12
Q

At less than ____ the strong nuclear force is ______

A

0.5 fm

repulsive

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13
Q

Between ____ and ____ the strong nuclear force is _______

A

0.5 fm
3.0 fm
attractive

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14
Q

Beyond ____ the strong nuclear force is ____

A

3.0 fm

zero

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15
Q

(In the nucleus) The electromagnetic force just acts between the ______ and is therefore ______

A

protons

repulsive

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16
Q

The electromagnetic force is much ______ than the strong nuclear force

A

weaker

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17
Q

The strong nuclear force acts between all of the _____ and has nothing to do with _____

A

nucleons

charge

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18
Q

What is an alpha particle?

A

a helium nucleus

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19
Q

What is the mass number?

A

the number of protons + the number of neutrons

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20
Q

What is the atomic number?

A

the number of protons

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21
Q

What is the atomic and mass number of an alpha particle?

A

mass number - 4

atomic number - 2

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22
Q

What is an alpha particle in terms of the energy it holds?

A

mono-energetic

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23
Q

What is a beta particle?

A

an electron

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24
Q

What is a beta particle in terms of the energy it holds?

A

has a range on energies

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25
What did the fact that an electron has a range of energies lead to the discovery of?
an antineutrino
26
What does an antineutrino do in beta decay?
shares the energy with the beta particle
27
Give three properties of a neutrino
1) neutral 2) very small mass (possibly mass-less) 3) therefore interacts very weakly (shares energy with electron in beta decay)
28
Define a photon
a discrete amount of energy that forms EM radiation with both particle and wave properties
29
What is the electromagnetic spectrum in order of ascending frequency?
1) radio 2) micro 3) infrared 4) visible light 5) ultra-violet 6) x-ray 7) gamma
30
Define 1 electrovolt
the energy an electron gains when it moves through a potential difference of 1V
31
What is 1 eV equal to in Joules?
1 eV = 1.6 x 10^-19 J
32
What is rest energy?
Energy due to mass
33
Describe pair production by a photon
1) a photon collides with a nucleus (the nucleus so that momentum is conserved) 2) if the photon has sufficient energy, a particle and an antiparticle are formed
34
What is the minimum energy of the photon equal to in pair production?
Emin = hf min = 2Eo
35
Why is the minimum energy needed in pair production equal to 2Eo?
- charge has to be conserved during the collision | - so two particles need to be made (a particle and an antiparticle)
36
Explain why there is a minimum energy required in pair production by a photon
1) energy of the photon needs to provide at least the rest masses 2) this is the energy needed to produce both a particle and an antiparticle of velocity 0 3) as the particle and the antiparticle have rest energies
37
What equation shows the energy in pair production by a photon?
hf = 2Eo + KE
38
If a photon of a higher energy is used in pair production, compared to a photon of lower energy, what are the two possible differences in the particles produced?
1) could make more particles | 2) could make the same number of particles but with more KE
39
When does annihilation occur?
When a particle meets its antiparticle
40
Define annihilation
the process by which a particle and its antiparticle meet and their mass gets converted into energy in the form of a pair of photons
41
Why are two photons produced in annihilation?
To conserve momentum
42
What equation shows the energy in annihilation?
2Eo (+ KE) = 2hf
43
Define a quark
a fundamental particle that makes up hadrons
44
Define a hadron
a composite subatomic particle made of two or more quarks held together by the strong nuclear force
45
Give an example of a hadron
proton | neutron
46
Define a baryon
a type of composite subatomic particle which contains three quarks (belong to the hadron family of particles)
47
Define a meson
hadronic subatomic particle composed of a quark-antiquark pair
48
Give an example of a meson
- pion | - kaon
49
Define a lepton
a fundamental particle that does not interact via the strong nuclear force (feels the weak force but not the strong force)
50
Give 4 examples of a lepton
1) electron 2) electron neutrino 3) muon 4) muon neutrino
51
What is the only stable free baryon?
the proton
52
What are cosmic rays?
very high energy particles from space
53
The existence of the neutrino was hypothesised to account for...
conservation of energy in beta decay
54
What are the two classes of hadrons?
1) baryons | 2) mesons
55
What do all baryons eventually decay to?
a proton
56
What does a muon decay into?
an electron
57
Define a pion
a type of meson that contains no strange quarks, it is the exchange particle of the strong nuclear force
58
Define a kaon
a type of meson which consists of one up or down quark and one strange quark, they decay into pions
59
What do kaons decay into?
pions
60
What is a boson?
a force carrying particle
61
Define fundamental particles
particles that are indivisible
62
The electromagnetic force affects all particle categories if they...
are charged
63
What must be conserved in all interactions?
- energy - momentum - charge - baryon number - lepton electron number - lepton muon number
64
Weak interactions cause quarks to...
decay (change flavour)
65
Strong interactions cause _____________ of quarks
pair production
66
Strangeness gives particles...
unusually long lifetimes
67
In what interactions are strange particles produced?
in strong interactions
68
In what interactions are strange particles conserved?
in strong interactions
69
Through what interactions do strange particles decay?
through weak interactions
70
In what interactions is strangeness not always conserved?
in weak interactions
71
What is the range of the electromagnetic force?
Infinite
72
What is the carrier particle for the electromagnetic force?
(virtual) photons
73
How strong in the weak nuclear force compared to the electromagnetic force?
10^-11 times EM
74
What is the carrier particles for the weak nuclear force?
- W+ - W- - (or Zo)
75
How strong in the strong nuclear force compared to the electromagnetic force?
100 times greater than EM
76
What are the carrier particles of the strong nuclear force?
Gluons (intranucleon) | Pions (internucleon)
77
Define electron capture
- When a proton in the nucleus captures an electron from the inner orbital - It generates a neutron and a neutrino
78
What must be seen on all Feynman diagrams?
- all conservation laws apply at each junction - paths diagonally to show movement through time - bosons shown with a wiggly line
79
What are the axis of a Feynman diagram?
y-axis: time | x-axis: space
80
Give 4 roles of exchange/carrier particles
- transfer momentum - transfer energy - transfer force - (sometimes) transfer charge
81
What is meant by an exchange/carrier particle?
- moves between one object/particle and another - gives rise to the force between the particles - transfer force, energy, momentum and sometimes charge

AQA A-Level Physics (21 decks)

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