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A-Level Physics > 2: Particles & Radiation > Flashcards

2: Particles & Radiation Flashcards

1
Q

Relative Charge & Mass of Proton, Neutron & Electron

A

Particle | Charge | Mass
Proton| +1 | 1
Neutron | 0 | 1
Electron | -1 | 0.0005

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2
Q

Nuclide Notation

A

Proton number is Z
Nucleon number is A
Atom is X

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3
Q

Isotope

A

Nuclei with the same atomic numbers, but different mass numbers

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4
Q

Strong Nuclear Force (5)

A
  • A fundamental force, which keeps nuclei stable
  • Closer than ~0.5 fm, there’s very-short range repulsion
  • In-between ~0.5 fm & ~3 fm, there’s short range attraction
  • Greater than ~3 fm, it has negligible effect
  • Only felt by quarks (so felt by protons & neutrons)
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5
Q

Decay in Unstable Nuclei

A

Alpha & Beta Decay

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6
Q

Equation for Alpha Decay

A

(A, Z)X → (A - 4, Z - 2)Y + (4, 2)α

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7
Q

Equation for Beta Minus Decay

A

(A, Z)X → (A, Z + 1)Y + e⁻ + ̅νₑ

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8
Q

Neutrino’s Existence

A

Was hypothesised to ensure conservation of energy in beta decay (energy difference between neutron and proton wasn’t completely filled by electron)

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9
Q

For Every Type of Particle ____

A

There is a corresponding antiparticle

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10
Q

Comparison of Particle & Antiparticle Properties

A

Equal mass & rest energy (in MeV) but opposite charges

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11
Q

Antiparticles of Proton, Electron, Neutron & Neutrino

A

Antiproton, positron, antineutron, antineutrino

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12
Q

Photon

A

A discrete packet of an electromagnetic wave (and the energy it carries)

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13
Q

Photon Energy Equation

A

E = h f = h c / λ

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14
Q

Energy of Laser Equation

A

E = n h f where n is number of photons

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15
Q

Pair Production

A

If there is enough energy density in a region, the energy is converted into mass producing a particle-antiparticle pair, travelling in opposite directions

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16
Q

Pair Production Examples (2)

A
  • A high energy photon can produce an electron-positron pair
  • Two protons (with high kinetic energy) may collide & produce an extra proton & antiproton
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17
Q

Minimum Energy needed for Pair Production

A

The total rest energy of the particle-antiparticle pair
Eₘᵢₙ = 2E₀
Eₘᵢₙ is the minimum energy for pair production in MeV
E₀ is the rest energy of a produced particle / antiparticle in MeV

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18
Q

Total Energy of Particles in Pair Production

A

Equal to the rest energy & kinetic energy of the photon

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19
Q

Annihilation

A

When a particle meets its corresponding antiparticle, all of their mass is converted into energy in the form of two high energy photons travelling in opposite directions

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20
Q

Minimum Energy of a Photon in Annihilation

A

Equal to the rest energy of the particle / antiparticle

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21
Q

Total Energy of Photons in Annihilation

A

Equal to the total rest energy and total kinetic energy of the particle-antiparticle pair

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22
Q

Fundamental Interactions (4)

A
  • Gravity
  • Electromagnetic
  • Weak nuclear
  • Strong nuclear (or strong interaction)
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23
Q

Exchange Particles

A

A concept (virtual / unreal), which explain forces between elementary particles

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24
Q

Exchange Particle for Electromagnetic Force

A

Virtual photon

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25
Q

What is the Weak Interaction Responsible for? (3)

A
  • Beta decay
  • Electron capture
  • Electron-proton collisions
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26
Q

Exchange Particles for Weak Interaction

A

W⁺ and W⁻ bosons

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27
Q

Beta- Decay Diagram

A

https://digestiblenotes.com/images/physics/alevel/feynman.png
Equation: n → p + e⁻ + ̅vₑ

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28
Q

Beta Plus Decay Diagram

A

Textbook page 44 figure 8
p⁺ → n + e⁺ + vₑ

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29
Q

Electron Capture

A

A nuclear proton interacts with an atomic electron (via the weak interaction), producing a neutron and electron neutrino (because the nucleus is proton-rich)

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30
Q

Electron Capture Diagram

A

https://digestiblenotes.com/images/physics/alevel/feynman6.png
p + e⁻ → n + vₑ

31
Q

Electron-Proton Collision

A

A high kinetic energy electron interacts with a proton (via the weak interaction), producing a neutron and electron neutrino

32
Q

Electron-Proton Collision Diagram

A

https://digestiblenotes.com/images/physics/alevel/feynman7.png
Equation: p + e⁻ → n + vₑ

33
Q

Hadrons are Subject to the ____

A

Strong interaction

34
Q

Classes of Hadrons (2)

A
  • Baryons (proton, neutron, 3 quarks) and antibaryons (antiproton, antineutron, 3 antiquarks)
  • Mesons (pion, kaon, quark and antiquark)
35
Q

Baryon Number

A

A quantum number, which is conserved in particle interactions

36
Q

Only Stable Baryon

A

The proton is the only stable baryon into which all other baryons will eventually decay

37
Q

Exchange Particle of Strong Nuclear Force

38
Q

____ is a Particle that Can Decay into Pions

39
Q

Leptons & Antileptons (4)

A
  • Electron & positron
  • Muon & antimuon
  • Electron neutrino & electron antineutrino
  • Muon neutrino & muon antineutrino
40
Q

Lepton Number

A

A quantum number, which is conserved in particle interactions for muon leptons and electron leptons individually (conservation of lepton type)

41
Q

____ is a Particle that Decays into Electrons

42
Q

Strange Particles are a Type of ____

43
Q

Production & Decay of Strange Particles

A

Produced through the strong interaction

Decay through the weak interaction

44
Q

Strangeness (s)

A

A quantum number, which is only conserved in strong interactions and shows strange particles are always created in pairs

45
Q

Strangeness can Change by ____ in Weak Interactions

A

0, +1 or -1

46
Q

Properties of Quarks & Antiquarks (3)

A
  • Charge
  • Baryon number
  • Strangeness
47
Q

Combinations of Quarks & Antiquarks (3)

A
  • Baryons
  • Antibaryons
  • Mesons
48
Q

Combinations of Quarks & Antiquarks for Baryons (2)

A
  • Proton = uud

- Neutron = udd

49
Q

Combinations of Quarks & Antiquarks for Antibaryons (2)

A
  • Antiproton = ̅u ̅u ̅d

- Antineutron = ̅u ̅d ̅d

50
Q

Combinations of Quarks & Antiquarks for Mesons (7)

A
  • π⁰ = u ̅u, d ̅d, s ̅s
  • π⁺ = u ̅d
  • π⁻ = d ̅u
  • K⁰ = d ̅s
  • ̅K⁰ = s ̅d
  • K⁺ = u ̅s
  • K⁻ = s ̅u
51
Q

Quarks (3)

A
  • Up (u)
  • Down (d)
  • Strange (s)
52
Q

Antiquarks (3)

A
  • Antiup ( ̅u)
  • Antidown ( ̅d)
  • Antistrange ( ̅s)
53
Q

Neutron Decay

A

Neutrons decay into protons by β⁻ decay

54
Q

Change of Quark Character in β⁻ & β⁺ decay (2)

A
  • β⁻: d → u

- β⁺: u → d

55
Q

Conservation Laws (4)

A
  • Charge
  • Baryon number
  • Lepton number
  • Strangeness
56
Q

____ & ____ are Conserved in Interactions

A

Energy, momentum

57
Q

Photoelectric Effect

A

A metal substance is irradiated with EM waves, which are greater than a certain frequency. The delocalised electrons may absorb a photon and gain enough energy to be emitted from the substance as photoelectrons

58
Q

Threshold Frequency

A

Minimum frequency of the EM radiation to produce the photoelectric effect. This is because the electron has to absorb a photon of a minimum energy to be emitted. The photoelectron will have 0 kinetic energy so: f₀ = Φ / h

59
Q

Work Function (Φ)

A

Minimum energy an electron needs to be emitted from a certain metal

60
Q

Stopping Potential

A

V_s is the pd needed to stop the photoelectrons with maximum kinetic energy by making them do work against the pd to lose their kinetic energy. e V_s = E_k(max)

61
Q

Photoelectricity Equation

A

h f = Φ + E_k(max)
hf is energy of photon in J
Φ is work function in J
E_k(max) is maximum kinetic energy of electron in J

62
Q

Excitation

A

An atomic electron gains the exact energy difference between two energy levels, so it moves to a higher energy level

63
Q

Ionisation

A

An electron, from the ground state of an atom, absorbs enough energy so it is emitted from the atom

64
Q

Fluorescent Tubes (6)

A
  • Fluorescent tubes contain mercury vapour, across which a high potential difference is applied
  • This accelerates free electrons, which ionise some mercury atoms, producing more free electrons
  • These free electrons collide with atomic electrons, exciting them to a higher energy level
  • When these electrons de-excite, they emit UV photons
  • Atomic electrons in a phosphor coating on the inside of the tube absorbs these photons, exiting them
  • When these electrons de-excite them emit visible light photons
65
Q

Electron Volt

A

The kinetic energy carried by an electron after it has been accelerated from rest through a potential difference of 1 V

66
Q

1 eV

A

= 1.6 x 10⁻¹⁹ J

67
Q

Line Emission Spectra

A

Photons are emitted from a hot element and the specific wavelengths of the photons produce bright lines on a black spectrum

68
Q

Line Absorption Spectra

A

White light is passed through a cool gas. Photons of specific wavelength are absorbed, which produce black lines on a continuous, bright spectrum

69
Q

Line Spectra are Evidence that ____

A

Electrons exist in discrete energy levels as elements always produce the same spectra so have the same energy levels in their atoms, which emit the same wavelengths of light when an electron moves between them

70
Q

Energy Levels Equation

A

h f = E₁ - E₂
E₁ & E₂ are the energy of energy levels 1 & 2 in J
hf is energy in J

71
Q

____ suggests particles possess ____

A

Electron diffraction, wave properties

72
Q

____ Suggests Electromagnetic Waves have ____

A

The photoelectric effect, a particulate nature

73
Q

De Broglie Wavelength Equation

A

λ = h / p = h / m v
λ is wavelength in m
h is the Planck constant in J s
p = mv is momentum in kg m s⁻¹

74
Q

Amount of Diffraction vs Momentum (3)

A
  • Increasing a particle’s momentum decreases its de Broglie wavelength
  • According to wave theory, the amount of diffraction and spread of lines in the diffraction pattern increases with the wavelength of the wave
  • Therefore, increasing momentum decreases the amount of diffraction and spread of lines in the diffraction pattern

A-Level Physics (9 decks)

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