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AQA PHYSICS ALEVEL > Particles & radiation > Flashcards

Particles & radiation Flashcards

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1
Q

What is the specific charge of a particle?

A

charge-mass ratio

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2
Q

What are isotopes?

A

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

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3
Q

What is the strong nuclear force?

A

keeps the nuclei stable by counteracting the electrostatic force of repulsion between protons in the nucleus.

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4
Q

What is the range of strong nuclear force?

A

-attractive up to 3fm
-repulsive below 0.5 fm

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5
Q

What happens to the numbers in alpha decay?

A

-proton number decreases by 2
-nucleon number decreases by 4

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6
Q

What is beta-minus decay?

A

Beta minus decay occurs in nuclei which are neutron-rich.

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7
Q

What happens to the numbers in beta minus decay?

A

-proton number increases by 1
-nucleon number stays the same.

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8
Q

What are photons?

A

EM radiation that travels in packets which transfer energy and have no mass.

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9
Q

What is the equation of the energy of a photon?

A

E=hf

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10
Q

What is Planck’s constant (h)?

A

6.63^10^-34

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11
Q

What is annihilation?

A

It is where a particle and its corresponding anti-particle collide and their masses are converted into energy.
-Energy (including KE of particles) is released in the form of two photons which travel in opposite directions.

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12
Q

Why do the photons travel in opposite directions in annihilation?

A

To conserve momentum?

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13
Q

Give one example of annihilation as an application?

A

PET scanner- introduce positron emitting radioisotope into patient where positrons are released and annihilate with electrons that are already in the patient, which emit gamma photons which can easily be detected.

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14
Q

What is pair production?

A

Where a photon is converted into matter and its corresponding anti-matter

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15
Q

What is the condition that pair production must occur in?

A

Energy of photon>total rest energy of both particles

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16
Q

What happens to the excess energy from pair production?

A

Any excess energy is converted into kinetic energy of the particles.

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17
Q

What force is responsible for beta plus decay?

A

Weak force

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18
Q

What force is responsible for beta minus decay?

A

Weak force

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19
Q

What is the general equation for beta-minus decay?

A

n–p+beta minus particle+anti-neutrino

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20
Q

What is the general equation for beta-plus decay?

A

p–n+beta plus particle+neutrino

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21
Q

What do unstable particles do?

A

They emit a particle and break down into a new nucleus and the nucleus transitions to a lower energy state to become more stable

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22
Q

What are the 4 fundamental forces?

A

gravity, electromagnetic, strong nuclear force, weak nuclear force

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23
Q

What are exchange particles?

A

They carry energy and momentum between particles

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24
Q

What is the exchange particle for a SNF?

A

gluon

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25
Q

What is the range of SNF?

A

3^10^-15m

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26
Q

What does SNF act on?

A

Hadrons

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27
Q

What is the exchange particle for weak force?

A

W boson (+/-)

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28
Q

What is the range of the weak force?

A

10^-18m

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29
Q

What does the weak force act on?

A

All particles.

30
Q

What is the exchange particle for electromagnetic force?

A

Virtual photon

31
Q

What is the range of the electromagnetic force?

A

Infinite

32
Q

What does the electromagnetic force act on?

A

charged particles

33
Q

What is the exchange particle for gravity?

A

Graviton

34
Q

What is the range for gravity?

A

Infinite

35
Q

What does gravity act on?

A

Particles with mass.

36
Q

What is responsible for electron capture and electron-proton collision?

A

Weak nuclear force

37
Q

What is the equation for electron capture and electron proton collision?

A

e^-+p–>n+Ve
electron+proton–>neutron+neutrino

38
Q

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

A

Electron-proton uses W^- exchange particle whereas electron capture uses W^+ exchange particle

39
Q

What is a fundamental particle?

A

They are particles that cannot be broken down into smaller particles and do not experience the SNF.

40
Q

What is the difference between hadrons and leptons?

A

Leptons are fundamental particles and hadrons are not.

41
Q

What are hadrons split into?

A

Baryons, anti-baryons and mesons.

42
Q

What is a baryon made up of?

A

Made from three quarks

43
Q

What is the quark make-up of a proton?

A

uud

44
Q

What is the quark make-up of a neutron?

A

udd

45
Q

What is the only stable baryon?

A

Proton- therefore all other baryons will eventually decay into a proton

46
Q

Which are heavier–> baryons and mesons or leptons?

A

baryons and mesons are heavier than leptons

47
Q

What are the 6 leptons?

A

-electron
-electron neutrino
-muon
-muon neutrino
-tauon
-tauon neutrino

48
Q

What is the lepton number for the 6 leptons?

A

+1

49
Q

What is the charge for any neutrino?

A

0

50
Q

What conservation laws must be obeyed for particle interactions to take place?

A

-charge
-baryon no
-lepton no
-strangeness

51
Q

What doesn’t have to be conserved in weak interactions?

A

strangeness

52
Q

What must have a strangeness of zero?

A

leptons

53
Q

How were muons discovered?

A

through the study of cosmic rays

54
Q

What is an electron’s anti-particle?

A

positron

55
Q

What do muons decay into?

A

electron

56
Q

How are strange particles produced and how do they decay?

A

Strange particles are produced via SN interaction but decay via the weak interaction.

57
Q

What do kaons decay into?

A

Pions, via the weak interaction.

58
Q

What are quarks?

A

Quarks are fundamental particles which make up hadrons.

59
Q

What are the 6 different quarks?

A

-up
-down
-strange
-charm
-top
-bottom

60
Q

What is the standard model?

A

It describes the fundamental particles & 3/4 fundamental forces that exist (not gravity).
-classifies ALL known particles.

61
Q

What is the photoelectric effect?

A

It is where photoelectrons are emitted from the surface of a metal after light above the threshold frequency is shone on it

62
Q

What is the threshold frequency?

A

The lowest frequency of light that has enough energy to emit photoelectrons.

63
Q

What is the work function?

A

It is the minimum energy required for electrons to be emitted from the surface

64
Q

What’s the difference between UV and visible light?

A

UV has a higher frequency hence more energy

65
Q

How can an electron gain energy to reach the work function?

A

Electrons can be given the energy through photons because when a photon collides with an electron it transfers all its energy to the electron.

66
Q

What happens if a photon has more energy than the work function?

A

The electron ionises and escapes but any excess energy is converted into the photoelectron’s KE.

67
Q

What happens if the photon has less energy than the work function?

A

The electron will not be able to ionise and escape but it may be excited to a higher energy level.

68
Q

What is the difference between electrons closer/further away from the metal surface?

A

Electrons closer to the metal surface will need less energy to escape than those deeper in the metal.

69
Q

What does increasing the intensity of the radiation incident on a metal surface do?

A

It increases the number of electrons emitted per second
- Increasing intensity=more photons bring emitted every second.
-hence more photons are hitting the surface of the metal hence more electrons are knocked off every second.

70
Q

What is max KE of emitted electrons dependent on/independent of?

A

Dependent on frequency
Independent of intensity
-More energy photon has, more it can transfer to the photoelectron as KE.

71
Q

What would the wave theory expect of the photoelectric effect?

A

-the trapped electrons would keep gaining energy from light as if it was acting as a wave-longer the light was shone, the more energy electron would gain.
-therefore low intensity/low frequency light would still eject electrons but would just take longer
-THIS HOWEVER DOESN’T HAPPEN SO WAVE THEORY IS WRONG!

72
Q
A

AQA PHYSICS ALEVEL (4 decks)

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