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2.Particles - A level Physics > 2.3 - Conservation Laws & Particle Interactions > Flashcards

2.3 - Conservation Laws & Particle Interactions Flashcards

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1
Q

What are the 4 fundamental forces/interactions?

A
  • Gravity
  • Electromagnetism
  • Strong nuclear (or strong interaction)
  • Weak nuclear
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2
Q

What is the weakest of the 4 fundamental forces?

A

Gravity

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3
Q

What is the strongest of the 4 fundamental forces?

A

Strong nuclear

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4
Q

What is the range of the weak force?

A

up to 10⁻¹⁸m.

(an atto-metre)

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5
Q

What are the fundamental interactions in order of strength?

A
  1. Strong
  2. Electromagnetism
  3. Weak
  4. Gravity
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6
Q

What do gravitational interactions only affect?

A

Particles with mass.

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7
Q

What do electromagnetic interactions only affect?

A

Particles with charge.

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8
Q

What do weak interactions only affect?

A

They actually affect all particles.

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9
Q

What do strong interactions only affect?

A

Hadrons (Baryons and Mesons).

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10
Q

When is a virtual/exchange particle created?

A

When 2 particles exert a force on each other (it is then formed).

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11
Q

What is the reason for an exchange particle?

A

To carry the fundamental force between each particle in the collision. (this is in a VERY short amount of time)

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12
Q

What are gauge bosons?

A

Exchange particles that mediate the 4 fundamental interactions.

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13
Q

What are the exchange particles of the strong interaction?

A

All pions (between nucleons).

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14
Q

What are the exchange particles of the weak interaction?

A

W⁺, W⁻ bosons.
(also Z⁰ but that’s not in the syllabus)

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15
Q

What are the exchange particles of the electromagnetic interaction?

A

Photon.
(specifically a gamma photon)

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16
Q

What are the exchange particles of the gravitational interaction?

A

Gravity is so weak it only has noticeable effects on large masses, so it doesn’t play a part in particle interactions.

17
Q

What are the 3 main properties of photons?

A
  • no mass
  • no charge
  • it is its own antiparticle
18
Q

Draw the Feynman diagram of the electromagnetic repulsion between 2 electrons.

A

Check online for answer.
(must include electrons going inwards and the virtual photon leave and the electrons going outwards)

19
Q

What are 2 examples of the weak interaction in action?

A

B- decay and B+ decay

20
Q

What is the equation of B- decay?

A

n -> p + e- + /Ve
neutron decays into a proton and lets out an electron and electron antineutrino

21
Q

What is the Feynman diagram of B- decay?

A

Check online.
(don’t forget W- boson as exchange particle)

22
Q

What is the equation for beta+ decay?

A

p –> n + e+ + Ve
proton decays into a neutron, positron and electron neutrino

23
Q

What is the Feynman diagram?

A

Check online.
(don’t forget the W+ boson as exchange particle)

24
Q

What is electron capture and what is the equation for it?

A

Electron capture is a weak interaction.
Electron capture is when an atomic electron is absorbed by a proton in the nucleus.
p + e- -> n + Ve

25
Q

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

A

Electron capture is when an atomic electron is absorbed by a proton in the nucleus and electron-proton collision is when an electron collides with a photon.
They bot have the same equation.

26
Q

What is the exchange particle of electron capture?

A

The W- boson.

27
Q

What is the exchange particle of electron-proton collision?

A

The W+ boson.

28
Q

What is the Feynman diagram for electron capture and electron-proton collision?

A

Check online
(they have different exchange particles btw).

29
Q

What are the 4 rules of drawing Feynman diagrams? (particle interaction diagrams)

A
  1. Incoming particles start at the bottom and move upwards.
  2. Baryons and leptons can’t cross from one side to the other.
  3. Charges on both sides must balance. W bosons carry charge from one side to the other.
  4. W- particles going to the left has the same effect as a W+ boson going to the right.
30
Q

What are the 6 conservation laws of particle interactions?

A
  • Charge
  • Baryon number
  • Lepton number
  • Strangeness
  • Energy (or mass-energy)
  • Momentum

2.Particles - A level Physics (5 decks)

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