Particles

Question 1

What are the main constituents of the atom?

Answer 1

*Proton
*Neutron
*Electron

Question 2

Define specific charge

Answer 2

Specific charge = charge / mass

Question 3

Specific charge of a proton?

Answer 3

Charge = 1.6x10^-19
Mass 1.67x10^-27

1.6x10^19/1.67x106-27 = 9.58x10^7

Question 4

What is the letter associated with proton number?

Answer 4

Z

Question 5

What is a nucleon?

Answer 5

A constituent of the nucleus : a proton or neutron

Question 6

What letter represents nucleon number?

Answer 6

A

Question 7

Which is correct: AXZ or ZXA?

Answer 7

AZX

Question 8

What is an isotope?

Answer 8

Two elements that have the same amount of protons but a different amount of neutrons

Question 9

State a use of radioactive isotopes

Answer 9

*Carbon dating - The proportion of carbon-14 in a material can be used to determine its age
*Cancer detection

Question 10

What is a strong nuclear force?

Answer 10

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

Question 11

Describe range of strong force

Answer 11

*Repulsive up to 0.5fm
*Attractive from 0.5-3fm
*Negligible past 3fm

Question 12

What makes a nucleus unstable?

Answer 12

Nuclei that have far too many protons, neutrons or both

Question 13

How do nuclei with too many nucleons decay?

Answer 13

Alpha decay

Question 14

How do nuclei with too many neutrons decay?

Answer 14

Beta minus decay (udd to uud)

Question 15

How is the existence of a neutrino hypothesised?

Answer 15

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

Question 16

What is meant by beta minus decay?

Answer 16

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

Question 17

What is an alpha particle?

Answer 17

A particle that contains two protons and two neutrons

Question 18

What is an antiparticle?

Answer 18

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

Question 19

Antiparticle of an electron

Answer 19

Positron

Question 20

Antiparticle of Pi0

Answer 20

Pi0

Question 21

What occurs when a particle and antiparticle meet?

Answer 21

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

Question 22

Pair production definition

Answer 22

A gamma ray photon is converted to a particle-antiparticle pair

Question 23

Min energy of a photon required to make a proton-antiproton pair

Answer 23

2 x proton rest energy
2 x 9.38.257 = 1876.514 MeV

Question 24

4 Fundamental forces

Answer 24

*Gravity
*Electromagnetic
*Weak nuclear
*Strong nuclear

Question 25

The virtual photon is the exchange particle of which force?

Answer 25

The electromagnetic force

Question 26

What type of particle is affected by the strong force?

Answer 26

Hadrons

Question 27

What is the exchange particle of the weak nuclear force?

Answer 27

W boson (W- or W+)

Question 28

What does the electromagnetic force act?

Answer 28

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

Question 29

When does weak nuclear interaction occur?

Answer 29

When a quark changes, it affects all types of particles

Question 30

What property must be conserved in particle interactions?

Answer 30

*Energy *Charge *Baryon number *Lepton number *Momentum *Strangeness

Question 31

What is a hadron

Answer 31

Both baryons and mesons are hadrons, made up of at least 2 quarks and interact via strong nuclear force

Question 32

Classes of hadrons

Answer 32

*Baryons - qqq *Mesons - quark antiquark

Question 33

Pion and kaon are both examples of which class of particles?

Answer 33

Mesons

Question 34

The pion can be a exchange particle for which force?

Answer 34

Strong nuclear force

Question 35

What particle does a kaon decay into?

Answer 35

A kaon decays into a pion

Question 36

Example of baryons

Answer 36

*Proton - uud *Neutron - ddu

Question 37

What is significant about a proton?

Answer 37

*The only stable baryon *All baryons will decay into protons

Question 38

Examples of leptons

Answer 38

*Muon *Electron *Neutrino

Question 39

Examples of leptons

Answer 39

*Muon *Electron *Neutrino

Question 40

What does a muon decay into?

Answer 40

An electron

Question 41

What is the strangeness value of a strange quark?

Answer 41

-1