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NSFC AQA A Level Physics 13A > 2.1 Particles > Flashcards

2.1 Particles Flashcards

1
Q

What are the main constituents of an atom?

A
  • Proton
  • Neutron
  • Electron
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2
Q

What is specific charge?

A

Specific charge=charge/mass
Units C kg-1<\sup>

Also known as Charge to Mass ratio

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3
Q

Define nucleon.

A

A constituent particle of a nucleus. Either a proton or a neutron.

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4
Q

What is nuclide notation?

A

  • X is the element
  • A is the nucleon or mass number (protons + neutrons)
  • Z is the proton number (or relative charge)
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5
Q

Define isotope.

A

Atom of an element with different number of neutrons and the same number of protons.

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6
Q

What is the strong nuclear force?

A

The fundamental force that binds nucleons together and stable in a nucleus.

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7
Q

What is the range and behaviour of the strong force?

A
  • Repulsive 0-0.5 fm
  • Attractive 0.5-3 fm
  • Negligible >3fm
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8
Q

What makes a nucleus unstable?

A

Too many nucleons; either protons, neutrons, or both.

A unstable nucleus wants to become a lighter stable nucleus by releasing energy.

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9
Q

How do nuclei with too many nucleons decay?

A

Alpha decay

The nucleus ejects an alpha particle

Where an alpha particle is a Helium nucleus

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10
Q

How do nuclei with too many neutrons decay?

A

Beta minus decay

A neutron turns into a proton

Where a beta minus particle is an electron

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11
Q

How do nuclei with too many protons decay?

A

Beta plus decay

A proton turns into a neutron

Where a beta plus particle is a positron

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12
Q

How was the existence of the neutrino hypothesised?

A

The energy of particles after beta decay was lower than before, a particle with 0 charge (to conserve charge) and negligible mass must carry away this excess energy, this particle is the neutrino.

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13
Q

True or false:
‘Every particle has a corresponding antiparticle’

A

True

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14
Q

What properties are different between a particle and its antiparticle?

A

All properties/quantum numbers are opposite except mass

For example: charge and strangeness

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15
Q

What are the antiparticles for
* proton
* neutron
* electron
* neutrino

A
  • antiproton
  • antineutron
  • positron
  • antineutrino
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16
Q

What is the photon model of EM radiation?

A

EM radiation consists of discrete packets (quanta) of energy

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17
Q

What is the equation for photon energy?

A
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18
Q

What is annilihation?

A

When a particle and its corresponding antiparticle meet, resulting in 2 gamma photons

For example

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19
Q

What is the minimum energy of 1 of the gamma photons in an annilihation?

A

Photon energy equals the rest energy of the particle

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20
Q

What is pair production?

A

When a gamma photon passes near a nucleus and produces a particle-antiparticle pair.

For example

21
Q

What is the minimum energy of the gamma photon in pair production?

A

Photon energy equals twice the rest energy of the particle

22
Q

What are the 4 fundamental forces/interactions?

A
  • Gravity
  • Electromagnetic
  • Weak
  • Strong
23
Q

What is an exchange particle/Boson?

A

A particle that transfers force between elementary particles

24
Q

What is the exchange particle for Electromagnetism?

A

(Virtual) Photon

25
Q

What particles does the Electromagnetic force act on?

A

Charged particles

For example: EM will act on a proton but not a neutron

26
Q

What are the exchange particles for the Weak force?

A

W+ and W- bosons

27
Q

When does the Weak force occur?

A

When there is a change in quark flavour

A way to identify a Weak interaction is if there are neutrinos present.

28
Q

What are the exchange particles for the Strong Nuclear force?

A

Pions

29
Q

What particles does the Strong force act on?

A

Hadrons

30
Q

What is the Feynman diagram for the scattering of 2 electrons?

A
31
Q

What is a hadron?

A
  • Baryons and Mesons are hadrons
  • Baryons are 3 quark
  • Mesons are a quark-antiquark
  • Bound by the Strong force

Hadrons are not fundamental particles

32
Q

What quantum number is associated with Baryons?

A

Baryon number.

Baryon number must be conserved.

33
Q

What is significant about the proton?

A

It is the only stable Baryon

Because it is the lightest Baryon. All Baryons decay towards protons.

Protons only decay when in a nucleus!

34
Q

What class of particles are Pions and Kaons?

A

Mesons

35
Q

What particle does a Kaon decay into?

A

Pion (plus other particles)

Think of the Kaon as a heavy cousin of the Pion.

36
Q

What are the Leptons?

A
  • Electron
  • Muon
  • Electron Neutrino
  • Muon Neutrino

Only feel the Weak force, and the chraged leptons also feel the EM force

37
Q

What quantum number is associated with Leptons?

A

Lepton number

There is also Lepton flavour number. All of which must be conserved.

38
Q

What does a Muon decay into?

A

Electron (plus other particles)

Think of the Muon flavours as heavy cousins of the electron flavours

39
Q

What do strange partices contain that non-strange particles do not?

A

At least one strange quark (or antiquark)

For example: the Kaons

40
Q

In what interactions are strange particles produced?

A

Strong interactions

41
Q

In what interactions do strange particles decay?

A

Weak interactions

42
Q

What quantum number is associated with strange particles?

A

Strangeness

Strange quark has -1 strangeness
Antistrange quark has +1 strangeness

43
Q

What force violates the conservation of strangeness?

A

Weak force

Strangeness can change by -1, 0, or 1 in weak interactions

44
Q

What are the quark compositions of the proton and the neutron?

A
  • Proton is uud
  • Neutron is udd
45
Q

What are the quark compositions of the pions?

A
46
Q

What are the quark compositions of the kaons?

A
47
Q

Write the decay equation for the neutron.

A

This is a beta minus decay

48
Q

What are all the conservation laws?

A
  • Energy
  • Momentum
  • Charge
  • Baryon number
  • Lepton number
  • Strangeness

Strangeness is violated by the Weak interaction

NSFC AQA A Level Physics 13A (19 decks)

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