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AQA A-Level Physics > Particles (AS) > Flashcards

Particles (AS) Flashcards

1
Q

For what range is the strong nuclear force positive?

A

0.5fm - 3fm

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2
Q

Why is the strong nuclear force repulsive at very small separations?

A

So that the nucleus doesn’t merge into a single point.

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3
Q

When does α (alpha) decay occur?

A

In very big/heavy nuclei.

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4
Q

What is an α particle made of?

A

Two neutrons and two protons.

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5
Q

When does β minus decay occur?

A

Neutron-rich nuclei.

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6
Q

What happens in β minus decay?

A

A neutron is changed into a proton.

(Nucleon number stays the same, proton number increases by 1).

A β minus particle is released.

An electron antineutrino is released.

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7
Q

When does β plus decay occur?

A

Proton-rich nuclei.

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8
Q

What happens in β plus decay?

A

A proton is changed into a neutron.

(Nucleon number stays the same, proton number decreases by 1).

A β plus particle is released.

An electron neutrino is released.

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9
Q

Neutrinos were first hypothesised due to observations of ______ _____. The energy of the particles was _____ than it was before, which didn’t fit with the principle of conservation of ______. Another particle had to carry away some of the missing energy.

A

Neutrinos were first hypothesised due to observations of (beta decay). The energy of the particles was (less) than it was before, which didn’t fit with the principle of conservation of (energy). Another particle had to carry away some of the missing energy.

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10
Q

All living things contain the same percentage of radioactive ______ taken in from the atmosphere.

After they die, the amount of ______ inside them ______over time as it decays to stable elemets.

Scientists can calculate the approximate age of dead organic matter by using the ______ data to find the percentage of ______ that’s left in the object.

A

All living things contain the same percentage of radioactive (carbon-14) taken in from the atmosphere.

After they die, the amount of (carbon-14) inside them (decreases) over time as it decays to stable elemets.

Scientists can calculate the approximate age of dead organic matter by using the (isotopic) data to find the percentage of (carbon-14) that’s left in the object.

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11
Q

Why might carbon dating not be reliable in the future?

A

Ratio of carbon-12 to carbon-14 altered by humans (burning fossil fuels -> more c-12, radioactive weapons -> more c-14).

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12
Q

What are photons?

A

Packets of electromagnetic radiation.

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13
Q

What is pair production?

A

If a photon has enough energy, it can convert itself into a particle-antiparticle pair.

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14
Q

What is the minimum energy for a photon to undergo pair production?

A

The minimum energy for a photon to undergo pair production is the total rest energy of the particles produced.

E(min) = hf(min) = 2Eo

Where Eo is rest energy.

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15
Q

What is annihiliation?

A

When a particle meets its antiparticle, all of the mass of the particle and antiparticle gets converted back to energy in the form of gamma ray photons.

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16
Q

What is the minimum energy for annihiliation to occur?

A

When a particle and anti particle meet, they annihilate, producing TWO photons.

For annihilation to occur, BOTH photons need to have a minimum energy, E(min), which added together equals at least 2Eo for energy to be conserved.

So, 2E(min) = 2Eo

and: E(min) = hf(min) = Eo

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17
Q

Name the four fundamental forces.

A

Gravity

Electromagnetic force

Weak force

Strong force

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18
Q

What is the exchange particle (or gauge boson) for the electromagnetic force?

A

Virtual photon, γ

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19
Q

What is the exchange particle (or gauge boson) for the weak force?

A

W+, W-

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20
Q

What is the exchange particle (or gauge boson) for the strong force?

A

Pions (π0, π+, π-)

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21
Q

Which particles does the electromagnetic force affect?

A

Charged particles only.

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22
Q

Which particles does the weak force affect?

A

All types.

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23
Q

Which particles does the strong force affect?

A

Hadrons only.

24
Q

In Feynman Diagrams, gauge bosons are represented by ______ ______ and other particles are represented by ______ ______.

A

In Feynman Diagrams, gauge bosons are represented by (wiggly lines) and other particles are represented by (straight lines).

25
Q

Rules of Feynman Diagrams:

  1. Incoming particles start at the ______ and move ______.
  2. The ______ and ______ can’t cross from one side of the diagram to another. (Left/Right)
  3. Make sure that the ______ on the top and bottom balance.
A

Rules of Feynman Diagrams:

  1. Incoming particles start at the (bottom) and move (upwards).
  2. The (baryons) and (leptons) can’t cross from one side of the diagram to another. (Left/Right)
  3. Make sure that the (charges) on the top and bottom balance.
26
Q

When does electron capture occur?

A

When an orbiting electron interacts with the nucleus and turns a proton into a neutron.

An electron neutrino is released.

27
Q

Give the equation for electron capture.

A

p + e- –> n + ν(e)

28
Q

Give the equation for beta-minus decay.

A

——————-_

n –> p + e- + ν(e)

29
Q

Give the equation for beta-plus decay.

A

p –> n + e+ + ν(e)

30
Q

Which gauge boson is responsible for electron capture?

A

W+

31
Q

Which gauge boson is responsible for beta-plus decay?

A

W+

32
Q

Which gauge boson is responsible for beta-minus decay?

A

W-

33
Q

What is the only stable baryon?

A

Proton.

All baryons except protons decay to a proton.

34
Q

What are pions?

A

Pions are the lightest mesons. π+, π- and πo.

35
Q

What are kaons?

A

Mesons that are heavier and more unstable than pions.

Ko

K+

K-
_
Ko

36
Q

Do leptons feel the strong force?

A

No

37
Q

Do baryons feel the strong force?

A

Yes

38
Q

Do mesons feel the strong force?

A

Yes

39
Q

Do hadrons feel the strong force?

A

Yes

40
Q

Give the quark composition of a π+ particle.

A

–_

ud

41
Q

Give the quark composition of a πo particle.

A

–——-

uu or dd

42
Q

Give the quark composition of a π- particle.

A

–_

du

43
Q

Give the quark composition of a K+ particle.

A

–_

us

44
Q

Give the quark composition of a Ko particle.

A

–_

ds

45
Q

———————————————–_

Give the quark composition of a Ko particle.

A

–_

sd

46
Q

Give the quark composition of a K- particle.

A

–_

su

47
Q

Give the quark composition of a proton.

A

uud

48
Q

Give the quark composition of an antiproton.

A

___

uud

49
Q

Give the quark composition of a neutron.

A

udd

50
Q

Give the quark composition of an antineutron.

A

___

udd

51
Q

Which interaction is strangeness NOT conserved in?

A

Weak interaction.

52
Q

Which interaction is strangeness conserved in?

A

Strong interaction.

53
Q

What are the three flavours of neutrinos?

A

Electron Neutrino (νe)

Muon Neutrino (νμ)

Tau Neutrino (ντ)

54
Q

What are the three categories of elementary particles?

A

Elementary particles:

Quarks
Leptons
Force Carriers

55
Q

List all quarks.

A

Quarks:

up / u
down / d
charm / c
strange / s
top / t
bottom / b
56
Q

List all leptons.

A

Leptons:

electron neutrino / νe
muon neutrino / νμ
tau neutrino / ντ
electron / e
muon / μ
tau / τ
57
Q

List all force carriers.

A

Force Carriers:

photon / γ
Z boson / Z
W boson / W
gluon / g

AQA A-Level Physics (14 decks)

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