Particles and Radiation

Question 1

What are the two main groups of particles?

Answer 1

All particles are put into the groups hadrons and leptons.

Question 2

What are leptons?

Answer 2

Leptons are fundamental particles including the electron, muon, and neutrino.

Question 3

What is the lepton number of leptons and their antiparticles?

Answer 3

Leptons have a lepton number of 1, while their antiparticle equivalents have a lepton number of -1.

Question 4

What types of neutrinos exist?

Answer 4

Neutrinos can be specifically electron neutrinos or muon neutrinos.

Question 5

How are hadrons classified?

Answer 5

Hadrons are split into baryons (made of 3 quarks) and mesons (made of 2 quarks).

Question 6

What are the three flavours of quarks?

Answer 6

The three flavours of quark are up, down, and strange.

Question 7

What is the charge of up, down, and strange quarks?

Answer 7

Up has a charge of +2/3, down and strange have a charge of -1/3.

Question 8

What is strangeness in quarks?

Answer 8

Only strange quarks have strangeness: -1 for a strange quark and +1 for an anti-strange.

Question 9

What is the baryon number of baryons?

Answer 9

Baryons have a baryon number that isn’t zero; it can be +1 or -1 if antiquarks are present.

Question 10

What are the compositions of neutrons and protons?

Answer 10

Neutrons are up, down, down; protons are up, up, down.

Question 11

What are pions and kaons?

Answer 11

Pions are mesons without strangeness, while kaons are mesons with strangeness.

Question 12

What is the exchange particle of the electromagnetic force?

Answer 12

The exchange particle is the photon.

Question 13

What is the exchange particle of the weak nuclear force?

Answer 13

The exchange particles are W+ and W- bosons or Z0 bosons.

Question 14

What is the exchange particle of the strong nuclear force?

Answer 14

The exchange particle is the pion or gluon.

Question 15

What happens when forces in a nucleus are balanced?

Answer 15

When balanced, a nucleus is stable.

Question 16

What is the range of the strong force?

Answer 16

The range of the strong force is 3 to 4 femtometers.

Question 17

What must be conserved in any interaction?

Answer 17

Charge, baryon number, and lepton numbers must be conserved.

Question 18

What is a Feynman diagram?

Answer 18

Feynman diagrams represent interactions, often involving W bosons for weak interactions.

Question 19

What happens in beta minus decay?

Answer 19

A down quark in a neutron decays into an up quark, turning it into a proton.

Question 20

What are strangeness rules in particle interactions?

Answer 20

Any interaction involving leptons must be weak; if only hadrons are involved and strangeness is conserved, it must be strong.

Question 21

What happens when strange particles decay?

Answer 21

Strangeness can change, but only by one in weak interactions.

Question 22

What is specific charge?

Answer 22

Specific charge is the charge to mass ratio for a particle.

Question 23

How is specific charge calculated?

Answer 23

Specific charge = charge in coulombs / mass in kilograms.

Question 24

What does radiation mean?

Answer 24

Radiation means any particle or wave emitted by something.

Question 25

What is gamma radiation?

Answer 25

Gamma radiation is emitted by the nucleus of an atom when it has excess energy.

Question 26

What is alpha decay?

Answer 26

Alpha decay occurs when a nucleus emits an alpha particle (2 protons and 2 neutrons).

Question 27

What happens in beta decay?

Answer 27

A neutron turns into a proton and an electron is emitted.

Question 28

What is annihilation in particle physics?

Answer 28

When a particle and its antiparticle meet, they can annihilate and convert their mass into energy.

Question 29

What is pair production?

Answer 29

Pair production occurs when a photon converts into two particles if it has enough energy.

Question 30

What are energy levels in an atom?

Answer 30

Electrons orbit the nucleus at specific energy levels, with n1 being the lowest.

Question 31

What is de-excitation?

Answer 31

De-excitation occurs when an excited electron falls back to a lower energy level, emitting photons.

Question 32

What is an emission spectrum?

Answer 32

An emission spectrum shows the various wavelengths of photons emitted by an object.

Question 33

What is an absorption spectrum?

Answer 33

An absorption spectrum shows wavelengths that are not transmitted through a gas or plasma.

Question 34

How do fluorescent lights work?

Answer 34

Electrons are accelerated through mercury gas, exciting it to emit UV photons, which are then converted to visible light.

Question 35

What is the photoelectric effect?

Answer 35

The photoelectric effect shows that light can liberate electrons from certain metals when it hits them.

Question 36

What is wave-particle duality?

Answer 36

Wave-particle duality refers to the concept that light and particles exhibit both wave-like and particle-like properties.

Question 37

What is the photoelectric effect?

Answer 37

The photoelectric effect is the phenomenon where light causes the liberation of electrons from certain metals.

Question 38

What happens when light shines on certain metals?

Answer 38

Electrons are liberated from the surface as they absorb energy as kinetic energy.

Question 39

How can we measure the liberation of electrons?

Answer 39

By placing the metal in an evacuated tube with an ammeter, a tiny current will flow as electrons cross the gap.

Question 40

What is the stopping potential (Vs)?

Answer 40

The stopping potential is the potential needed to oppose the current until it reaches zero.

Question 41

What is the relationship between kinetic energy and stopping potential?

Answer 41

The kinetic energy an electron has is equal to q times Vs or e times Vs.

Question 42

What does the graph of maximum kinetic energy against frequency show?

Answer 42

It results in a straight line, with the gradient representing Planck's constant.

Question 43

What does it mean if the line does not go through the origin?

Answer 43

It indicates that the electron does not gain as much kinetic energy as the photon's energy due to energy loss during liberation.

Question 44

What is the work function?

Answer 44

The work function is the minimum energy required for an electron to be liberated from the surface of a metal.

Question 45

What is the threshold frequency (f0)?

Answer 45

The threshold frequency is the minimum frequency needed to liberate an electron.

Question 46

What is the equation relating kinetic energy, photon energy, and work function?

Answer 46

The equation is Ek max = hf - φ.

Question 47

What does the equation Ek max = hf - φ represent?

Answer 47

It represents the kinetic energy left over for the electron after liberation, equal to the photon energy minus the work function.

Question 48

What proves the particle theory of light?

Answer 48

If the frequency of light isn't high enough, electrons won't be liberated, demonstrating a one-to-one interaction between photons and electrons.

Question 49

What is electron diffraction?

Answer 49

Electron diffraction is the phenomenon observed when electrons create an interference pattern, indicating their wave nature.

Question 50

What is the de Broglie wavelength equation?

Answer 50

The de Broglie wavelength equation is λ = h / mv, where h is Planck's constant and mv is the momentum of the particle.

Question 51

What is the relationship between speed and wavelength?

Answer 51

Faster speed results in a smaller wavelength, leading to less diffraction.

Question 52

How is kinetic energy related to momentum?

Answer 52

Kinetic energy (KE) is equal to half mv squared, and can be converted to momentum (p) using the relationship p = mv.

Question 53

In what way do particles decay and compare what Neutrons decay into and what Kaons decay into

Answer 53

Particles decay from heaviest to lightest. Baryons can only decay into lighter Baryons, ending with the proton which is the lightest, and nothing else. Kaons decay into pions whereas neutrons decay into protons.

Question 54

How is the Lepton number conserved when in relation to electrons or muons

Answer 54

Electrons and Electron-Neutrino have a +1 Lepton-Electron number (-1 for anti versions of particles). Muons and Muon-Neutrino have a +1 Lepton-Muon number (-1 for anti versions of particles).

Question 55

What are Quarks?

Answer 55

Fundamental particles that are the building blocks for Hadrons. Their properties make up the properties of a particle (e.g. Proton has +1 charge because the quarks that make it up has an overall charge of +1).

Question 56

Compare how you would calculate the Specific Charge for Nuclei and for Ions

Answer 56

For nuclei you would do the (Charge of a Proton X the Number of Protons) divided by (Mass of Nucleons X Number of Nucleons). For Ions

Question 57

Highlight the difference between the Particle Interactions of Electron Capture and Electron-Proton Collision

Answer 57

→Both have Proton + Electron ‒‒> Neutron + Neutrino However the difference is in their exchange particles. In Electron Capture it has an exchange particle of W+ Boson going in the direction of lighter particles

Question 58

State the hypothesis of Neutrinos

Answer 58

Observations of Beta decay found energy after was less than before it which violates conservation of energy law. So another particle must exist to provide that missing energy leading to discovery of the Neutrino.

Question 59

Describe what the purpose of Exchange Particles are

Answer 59

All forces are caused by particle exchange. When two particles interact and exert a force on one another something must happen to let one particle know that the other one's there.

Question 60

What is Isotopic Data and an Application of it?

Answer 60

The relative amounts of different isotopes of an element present in a substance. An application would be Carbon Dating (More explored in Nuclear Physics)