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Physics > Particles > Flashcards

Particles Flashcards

1
Q

what are the 3 constituents that makes up an atom

A

protons neutron and electrons

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2
Q

what is found at the center of an atom and what is it made up of

A

a nucleus and is made up of protons and neutrons

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3
Q

what are protons and neutrons also known as

A

nucleons

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4
Q

where are electrons found in an atom

A

they are found in shells orbiting the nucleus

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5
Q

what is the charge of a proton neutron and electron

A

proton - +1.6x10^-19
electron - -1.6x10^-19
neutron - 0

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6
Q

what is the relative charge of a proton neutron and electron

A

proton - +1
electron - -1
neutron - 0

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7
Q

what is the mass of a proton neutron and electron

A

proton and neutron - 1.67x10^-27
electron - 9.11x10^-31

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8
Q

what is the relative mass of a proton neutron and electron

A

proton and neutron - 1
electron - 0.0005

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9
Q

what is the specific charge of a proton neutron and electron

A

proton - 9.58x10^7
neutron - 0
electron - 1.76x10^11

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10
Q

what are the units for specific charge

A

CKg^-1

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11
Q

what is the specific charge of a particle and how do you calculate it

A

the charge-mass ratio and is calculated by dividing a particles charge by its mass

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12
Q

what is an isotope

A

are atoms with the same number of protons but different numbers of neutrons

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13
Q

what is an example of an isotope

A

carbon-14 is a radioactive isotope of carbon which can be used to find the approximate age of an object containing organic material. this is done through carbon dating, which involves calculating the percentage of carbon-14 remaining in the object, and using the known starting value of carbon-14 and its half life to calculate an approximate age

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14
Q

how does the strong nuclear force keep the nuclei stable

A

by counteracting the electrostatic force of repulsion between protons in the nucleus(as they have the same charge). it only acts on nucleons and has a very short range, where it is attractive up to separations of 3 fm, but repulsion below separations of 0.5 fm,

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15
Q

what causes an unstable nuclei

A

when an atom has too many of either protons, neutrons or both causing the SNF to not be enough to keep them stable, therefore these nuclei will decay in order to become stable. the type of decay the nuclei will experience depends on the amount of each nucleon in them

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16
Q

where does alpha decay occur

A

in a large nuclei, with too many of both protons and neutrons

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17
Q

in the equation for alpha decay what happens to the proton number and nucleon number

A

the proton number decreases by 2
the nucleon number decreases by 4

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18
Q

where does beta minus decay occur

A

in nuclei which are neutron-rich (have too many neutrons)

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19
Q

what happens the the proton number and nucleon number in the equation for beta minus decay

A

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

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20
Q

how did scientists theorize that there is a neutrino in beta minus decay

A

at first, scientists believed that only an electron was emitted from the nucleus during beta minus decay, however observations of the energy levels of the particles before and after the decay showed that energy was not conserved. this does not follow the principle of conservation of energy, and therefore neutrinos were hypothesized to account fir this, and later they were observed

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21
Q

what is there for every type of particle

A

an antiparticle

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22
Q

what do antiparticles have the same as the particle

A

the same rest energy and mass but all other properties are opposite

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23
Q

what is the antiparticle of an electron and neutrino

A

positron and antineutrino

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24
Q

what do electromagnetic radiation travel in

A

packets called photons which transfer energy and have no mass

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25
Q

what is the energy of photons directly proportional to

A

the frequency of electromagnetic radiation

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26
Q

what equation shows that the energy of photons is directly proportional to the electromagnetic radiation

A

E = hf = (hc/lambda)

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27
Q

what is the value of plancks constant

A

6.63x10^-34 Js

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28
Q

what is annihilation

A

is where a particle and its corresponding antiparticle collide, as a result their masses are converted into energy

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29
Q

what is the energy during annihilation released as

A

is released in the form of two protons moving in opposite directions in order to conserve momentum

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30
Q

what is an application of annihilation and how does it work

A

is used in a PET scanner
this allows 3D images of the inside of the body to be taken, therefore making medical diagnoses easier. this is done by introducing a positron-emitting radioisotope into the patient, as positrons are released they annihilate with electrons already in the patients system, emitting gamma photons which can easily be detected

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31
Q

what is pair production

A

is where a photon is converted into n equal amount of matter and antimatter. this can only occur when the photon has an energy greater than the total rest energy of both particles, any excess energy is converted into kinetic energy of the particles

32
Q

what are the 4 fundamental forces

A

gravity
electromagnetic
weak nuclear (WNF)
strong nuclear (SNF)

33
Q

what are forces between particles caused by

A

exchange particles

34
Q

what do exchange particles do

A

they carry energy and momentum between the particles experiencing the force and each fundamental force has its own exchange particles

35
Q

if the interaction is strong what is the exchange particle, range and what does it act on

A

exchange particle - gluon
range - 3x10^-15
acts on - hadrons

36
Q

if the interaction is weak what is the exchange particle, range and what does it act on

A

exchange particle - W boson (W+ OR W-)
range - 10^-18
acts on - all particles

37
Q

if the interaction is electromagnetic what is the exchange particle, range and what does it act on

A

exchange particle - virtual photon
range - infinite
acts on - charged particles

38
Q

if the interaction is gravity what is the exchange particle, range and what does it act on

A

exchange particle - graviton
range - infinite
acts on - particles with mass

39
Q

what is the nuclear force responsible for

A

beta decay, electron capture, and electron-proton collisions all of which can be represented as the particle interaction diagrams

40
Q

what is the equation for electron capture and electron-proton collision

A
  • p + e- –> n + Ve
41
Q

what is different about electron capture and electron-proton collisions

A

they have different exchange particles

42
Q

what is the equation for beta plus decay

A

p –> n + e+ +Ve

43
Q

what is the equation for beta minus decay

A

n –> p + e- + -Ve

44
Q

what are all particles classified as

A

either hadrons or leptons

45
Q

what is the difference between leptons and hadrons

A

leptons are fundamental particles

46
Q

what classifies a particles as a fundamental particle

A

they cannot be broken down any further and they do not experience a strong nuclear force

47
Q

what are hadrons formed from

A

quarks

48
Q

what can hadrons be further separated into

A

baryons, antibaryons and mesons

49
Q

what are baryons formed of

A

3 quarks

50
Q

what are antibaryons formed of

A

3 antiquarks

51
Q

what are mesons formed from

A

a quark and a antiquark

52
Q

what does the baryon number show

A

shows whether it is a baryon (if 1), an antibaryon (if -1), or not a baryon (if 0)

53
Q

what is the only stable baryon

A

a proton, therefore all baryons will eventually decay into a proton either directly or indirectly

54
Q

what does the lepton number show

A

shows whether it is a lepton (if 1), antilepton (if-1) and not a lepton (if 0)

55
Q

what are the two types of lepton numbers

A

electron lepton number
muon lepton number

56
Q

are baryon numbers and lepton numbers conserved in particle interactions

A

yes

57
Q

what is a muon also known as and what does it decay into

A

a ‘heavy electron’ and decays into an electron

58
Q

what are strange particles

A

are particles which are produced by the strong nuclear interaction but decay by the weak interaction

59
Q

what are the strange particles you need to know about

A

a kaon which decay into pions through the weak interaction

60
Q

what is strangeness

A

is a property of particles which shows that strange particles must be created in pairs, as strangeness must be conserved in strong interactions however in weak interactions strangeness can change by 0,+1,-1

61
Q

what is needed to investigate particle physics but what are the cons

A

particle accelerators however they are expensive to build and run and also produce high amounts of data, scientific investigations rely on collaboration of scientists internationally

62
Q

what are quarks

A

are fundamental particles which make up hadrons

63
Q

what are the three types of quarks

A

up, down, strange

64
Q

what is the charge baryon number and strangeness of an up quark

A

charge - +2/3e
baryon number - +1/3
strangeness - 0

65
Q

what is the charge baryon number and strangeness of a down quark

A

charge - -1/3e
baryon number - +1/3
strangeness - 0

66
Q

what is the charge baryon number and strangeness of a strange quark

A

charge - -1/3e
baryon number - +1/3
strangeness - -1

67
Q

when quarks combine what do they form

A

baryons and mesons

68
Q

how do you find the quark combination of an antibaryon

A

if you know the quark combination of the baryon is to simply change the quarks into their respective antiquarks. also true for mesons

69
Q

as all baryons decay into protons what else will decay into a proton

A

a neutron

70
Q

what is the equation for neutron or baryon decay

A

n –> p + e- + -Ve

71
Q

what properties must always be conserved in particle interactions

A

-energy and momentum
-charge
-baryon number
-electron lepton number
-muon lepton number

72
Q

what is conserved in only strong interactions

A

strangeness

73
Q

how do you show these conservation laws are obeyed in an interaction

A

you must find the value of each property before and after the interaction and make sure they are equal

74
Q

what causes beta minus and beta plus decay

A

by the weak interaction because there is a change in quark type

75
Q

in beta minus decay what must happen to the quark in order for a neutron to become a proton

A

a down quark must change into an up quark

76
Q
A

Physics (18 decks)

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