Particles & radiation

Question 1

What is the specific charge of a particle?

Answer 1

charge-mass ratio

Question 2

What are isotopes?

Answer 2

Atoms with the same number of protons but different number of neutrons.

Question 3

What is the strong nuclear force?

Answer 3

keeps the nuclei stable by counteracting the electrostatic force of repulsion between protons in the nucleus.

Question 4

What is the range of strong nuclear force?

Answer 4

-attractive up to 3fm
-repulsive below 0.5 fm

Question 5

What happens to the numbers in alpha decay?

Answer 5

-proton number decreases by 2
-nucleon number decreases by 4

Question 6

What is beta-minus decay?

Answer 6

Beta minus decay occurs in nuclei which are neutron-rich.

Question 7

What happens to the numbers in beta minus decay?

Answer 7

-proton number increases by 1
-nucleon number stays the same.

Question 8

What are photons?

Answer 8

EM radiation that travels in packets which transfer energy and have no mass.

Question 9

What is the equation of the energy of a photon?

Answer 9

E=hf

Question 10

What is Planck’s constant (h)?

Answer 10

6.63^10^-34

Question 11

What is annihilation?

Answer 11

It is where a particle and its corresponding anti-particle collide and their masses are converted into energy.
-Energy (including KE of particles) is released in the form of two photons which travel in opposite directions.

Question 12

Why do the photons travel in opposite directions in annihilation?

Answer 12

To conserve momentum?

Question 13

Give one example of annihilation as an application?

Answer 13

PET scanner- introduce positron emitting radioisotope into patient where positrons are released and annihilate with electrons that are already in the patient, which emit gamma photons which can easily be detected.

Question 14

What is pair production?

Answer 14

Where a photon is converted into matter and its corresponding anti-matter

Question 15

What is the condition that pair production must occur in?

Answer 15

Energy of photon>total rest energy of both particles

Question 16

What happens to the excess energy from pair production?

Answer 16

Any excess energy is converted into kinetic energy of the particles.

Question 17

What force is responsible for beta plus decay?

Answer 17

Weak force

Question 18

What force is responsible for beta minus decay?

Answer 18

Weak force

Question 19

What is the general equation for beta-minus decay?

Answer 19

n–p+beta minus particle+anti-neutrino

Question 20

What is the general equation for beta-plus decay?

Answer 20

p–n+beta plus particle+neutrino

Question 21

What do unstable particles do?

Answer 21

They emit a particle and break down into a new nucleus and the nucleus transitions to a lower energy state to become more stable

Question 22

What are the 4 fundamental forces?

Answer 22

gravity, electromagnetic, strong nuclear force, weak nuclear force

Question 23

What are exchange particles?

Answer 23

They carry energy and momentum between particles

Question 24

What is the exchange particle for a SNF?

Answer 24

gluon

Question 25

What is the range of SNF?

Answer 25

3^10^-15m

Question 26

What does SNF act on?

Answer 26

Hadrons

Question 27

What is the exchange particle for weak force?

Answer 27

W boson (+/-)

Question 28

What is the range of the weak force?

Answer 28

10^-18m

Question 29

What does the weak force act on?

Answer 29

All particles.

Question 30

What is the exchange particle for electromagnetic force?

Answer 30

Virtual photon

Question 31

What is the range of the electromagnetic force?

Answer 31

Infinite

Question 32

What does the electromagnetic force act on?

Answer 32

charged particles

Question 33

What is the exchange particle for gravity?

Answer 33

Graviton

Question 34

What is the range for gravity?

Answer 34

Infinite

Question 35

What does gravity act on?

Answer 35

Particles with mass.

Question 36

What is responsible for electron capture and electron-proton collision?

Answer 36

Weak nuclear force

Question 37

What is the equation for electron capture and electron proton collision?

Answer 37

e^-+p-->n+Ve electron+proton-->neutron+neutrino

Question 38

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

Answer 38

Electron-proton uses W^- exchange particle whereas electron capture uses W^+ exchange particle

Question 39

What is a fundamental particle?

Answer 39

They are particles that cannot be broken down into smaller particles and do not experience the SNF.

Question 40

What is the difference between hadrons and leptons?

Answer 40

Leptons are fundamental particles and hadrons are not.

Question 41

What are hadrons split into?

Answer 41

Baryons, anti-baryons and mesons.

Question 42

What is a baryon made up of?

Answer 42

Made from three quarks

Question 43

What is the quark make-up of a proton?

Answer 43

uud

Question 44

What is the quark make-up of a neutron?

Answer 44

udd

Question 45

What is the only stable baryon?

Answer 45

Proton- therefore all other baryons will eventually decay into a proton

Question 46

Which are heavier--> baryons and mesons or leptons?

Answer 46

baryons and mesons are heavier than leptons

Question 47

What are the 6 leptons?

Answer 47

-electron -electron neutrino -muon -muon neutrino -tauon -tauon neutrino

Question 48

What is the lepton number for the 6 leptons?

Answer 48

+1

Question 49

What is the charge for any neutrino?

Answer 49

0

Question 50

What conservation laws must be obeyed for particle interactions to take place?

Answer 50

-charge -baryon no -lepton no -strangeness

Question 51

What doesn't have to be conserved in weak interactions?

Answer 51

strangeness

Question 52

What must have a strangeness of zero?

Answer 52

leptons

Question 53

How were muons discovered?

Answer 53

through the study of cosmic rays

Question 54

What is an electron's anti-particle?

Answer 54

positron

Question 55

What do muons decay into?

Answer 55

electron

Question 56

How are strange particles produced and how do they decay?

Answer 56

Strange particles are produced via SN interaction but decay via the weak interaction.

Question 57

What do kaons decay into?

Answer 57

Pions, via the weak interaction.

Question 58

What are quarks?

Answer 58

Quarks are fundamental particles which make up hadrons.

Question 59

What are the 6 different quarks?

Answer 59

-up -down -strange -charm -top -bottom

Question 60

What is the standard model?

Answer 60

It describes the fundamental particles & 3/4 fundamental forces that exist (not gravity). -classifies ALL known particles.

Question 61

What is the photoelectric effect?

Answer 61

It is where photoelectrons are emitted from the surface of a metal after light above the threshold frequency is shone on it

Question 62

What is the threshold frequency?

Answer 62

The lowest frequency of light that has enough energy to emit photoelectrons.

Question 63

What is the work function?

Answer 63

It is the minimum energy required for electrons to be emitted from the surface

Question 64

What's the difference between UV and visible light?

Answer 64

UV has a higher frequency hence more energy

Question 65

How can an electron gain energy to reach the work function?

Answer 65

Electrons can be given the energy through photons because when a photon collides with an electron it transfers all its energy to the electron.

Question 66

What happens if a photon has more energy than the work function?

Answer 66

The electron ionises and escapes but any excess energy is converted into the photoelectron's KE.

Question 67

What happens if the photon has less energy than the work function?

Answer 67

The electron will not be able to ionise and escape but it may be excited to a higher energy level.

Question 68

What is the difference between electrons closer/further away from the metal surface?

Answer 68

Electrons closer to the metal surface will need less energy to escape than those deeper in the metal.

Question 69

What does increasing the intensity of the radiation incident on a metal surface do?

Answer 69

It increases the number of electrons emitted per second - Increasing intensity=more photons bring emitted every second. -hence more photons are hitting the surface of the metal hence more electrons are knocked off every second.

Question 70

What is max KE of emitted electrons dependent on/independent of?

Answer 70

Dependent on frequency Independent of intensity -More energy photon has, more it can transfer to the photoelectron as KE.

Question 71

What would the wave theory expect of the photoelectric effect?

Answer 71

-the trapped electrons would keep gaining energy from light as if it was acting as a wave-longer the light was shone, the more energy electron would gain. -therefore low intensity/low frequency light would still eject electrons but would just take longer -THIS HOWEVER DOESN'T HAPPEN SO WAVE THEORY IS WRONG!