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A Level Physcis > Particles > Flashcards

Particles Flashcards

1
Q

What are the main constituents of an atom

A

A proton, neutron, electron

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2
Q

What is meant by specific charge

A

Specific charge = charge/mass

Units C/kg

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3
Q

What is the specific charge of a proton

A

Charge: +1.6 x 10^-19
Mass: 1.67 x 10^-27kg

Specific charge: 9.58 x10^7 C/kg

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4
Q

What is the letter associated with the proton number?

A

Z

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5
Q

What is a nucleon?

A

The parts of a nucleus: a proton or a neutron.

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6
Q

What letter represents nucleon number?

A

A

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7
Q

What is the correct notation?

A Z
X X
Z A

A

A
X
Z

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8
Q

What is an isotope?

A

A version of an element with the same number of protons but a different number of neutrons.

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9
Q

State a use of radioactive isotopes.

A

Carbon dating - the proportion of carbon-14 in a material can be used to estimate age.

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10
Q

What is the strong nuclear force?

A

The fundamental force that keeps the nucleus stable by counteracting the electrostatic force of repulsion between protons.

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11
Q

Describe the range of the strong force?

A
  • Repulsive up to 0.5fm
  • Attractive from 0.5-3fm
  • Negligible past 3fm
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12
Q

What makes a nucleus unstable?

A

Nucleus which have too many of either protons or neutrons or both.

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13
Q

How do nuclei with too many nucleons decay?

A

Alpha decay, which is the emission of a helium nucleus formed of 2 protons and 2 neutrons.

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14
Q

How do nuclei with too many neutrons decay?

A

Beta minus decay in which a neutron decays to a proton by the weak interaction (quark character has changed from udd to uud)

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15
Q

How was the existence of the neutrino hypothesised?

A

The energy of particles after beta decay was lower that 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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16
Q

What is meant by beta minus decay?

A

When a neutron into a proton, the atom releases an electron and an anti-electron neutrino.

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17
Q

What is an alpha particle?

A

A particle contains two protons and two neutrons, the same as a helium nucleus.

18
Q

What is an anti particle?

A

For each particle there is an antiparticle with the same rest energy and mass but all other properties are the opposite of its respective particle.

19
Q

True of False:
Every particle has a antiparticle

A

True

20
Q

What is the name of the antiparticle of an electron?

A

Positron

21
Q

What is the antiparticle of a pion 0

A

Pion 0, since it is an antiparticle itself.

22
Q

What occurs when a particle and antiparticle meet?

A

Annihilation:

The mass of the particle and antiparticle is converted back to energy in the form of 2 gamma ray photons which go in opposite directions to conserve momentum.

23
Q

What is pair production?

A

A gamma ray photon is converted into a particle-antiparticle pair.

24
Q

What is the minimum energy of a photon required to make a proton-antiproton pair?

A

2 x proton rest energy:

2 x 938.257 = 1876.514 MeV

25
Q

What are the 4 fundamental forces

A
  • Gravity
  • Electromagnetic
  • Weak nuclear
  • Strong nuclear
26
Q

The virtual photon is the exchange particle of which force?

A

The electromagnetic force.

27
Q

What type of particles are affected by the strong nucleus force?

A

Hadrons.

28
Q

What is the exchange particle of the weak nuclear force?

A

The W boson

29
Q

What does the electromagnetic force act on?

A

It acts on charged objects, for example when a positively charged ball repels another positively charged ball.

30
Q

When does weak nuclear interaction occur?

A

When quark character changes

31
Q

What properties must be conserved in particle interactions?

A
  • Energy
  • Charge
  • Baryon number
  • Lepton number
  • Momentum
  • Strangeness (only for strong interactions)
32
Q

What is a hadron?

A

Both baryons and mesons are hadrons, hadrons are made of 2 or more quarks held together by the strong nuclear force.

33
Q

What are the classes of hadrons?

A
  • Baryons (three quarks )
  • Mesons (1 quark, 1 antiquark)
34
Q

The pion and kaon are both examples of which class of particles?

A

Mesons

35
Q

The pions can be exchange particle for which force?

A

The strong nuclear force.

36
Q

Which particle does kaons decay into?

A

A kaon decays into a pion.

37
Q

Give some examples of baryons.

A

Proton - uud
Neutron - ddu

38
Q

What is significant about a proton?

A
  • It is the only stable baryon
  • All baryons will eventually decay into protons
39
Q

What are some examples of leptons?

A
  • Electron
  • Muon
  • Neutrino
  • (the antiparticles of the above)
40
Q

What does a muon decay into?

A

An electron and two types of neutrino.

41
Q

What is the strangeness value of a strange quark

A
  • 1
42
Q

True or False: ‘ strangeness is always conserved in a weak interaction’

A

False - strangeness is only conserved in the strong interaction, in weak interactions it can change by 0, -1 and +1

A Level Physcis (7 decks)

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