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Particles & Radiation Flashcards

(75 cards)

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1
Q

What is the relative mass/charge of a proton/neutron/electron

A

Charge - P = +1 / N = 0 / E = -1
Mass - P = 1 / N = 1 / E = 0.0005

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2
Q

What is alpha emission

A

When an element emits and alpha particle and loses 2 protons & 2 neutrons (4 nucleons)

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3
Q

What is beta minus emission

A

When an element has a neutron rich nucleus and a neutron decays into a proton. The reaction releases a beta - particle and an anti electron neutrino

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4
Q

What is beta plus emission

A

When an element has a proton rich nucleus and proton decays into a neutron. The reaction releases a beta + particle and an electron neutrino

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5
Q

When does alpha emission occur

A

Very big nuclei

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6
Q

How did scientists know an extra particle was released during beta emission

A

The (anti)electron neutrino carries some energy and momentum (conservation laws)

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7
Q

What are the properties of antiparticles respective to their opposite particles

A

Same mass/rest mass
Opposite charges

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8
Q

What are photons

A

Packets of EM radiation

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9
Q

What happens when you convert energy to mass

A

Equal amounts of matter & antimatter are created

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10
Q

What ray needs to be present for pair production and why

A

Gamma because its the only ray which carries that amount of energy

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11
Q

What is produced from pair production

A

Particle & anti particle pair

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12
Q

What happens in annihilation

A

A particle & anti particle pair interact and all mass converts into energy.

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13
Q

Why don’t antiparticles exist for long

A

They exist for fractions of a second before they annihilate

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14
Q

Equation for rest energy

A

Rest mass x speed of light^2

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15
Q

What is a repulsive force

A

When a force pushes two objects away from each other

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16
Q

What is an attractive force

A

When a force pushes two objects together

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17
Q

What are the 4 fundamental forces

A

Strong/weak nuclear
Gravity
EM

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18
Q

Why is gravity not used in particles

A

Force created by gravity is negligible because of mass of particle

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19
Q

What gauge bosons and particles does EM interactions have

A

Virtual photons, Affects charged particles only

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20
Q

What gauge bosons and particles does weak nuclear interactions have and what types of particles does it affect

A

W+/- bosons, Affects all types of particles

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21
Q

What gauge bosons and particles does strong nuclear interactions have

A

Pions, Only affects hadrons

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22
Q

What is the Feynman diagram of Particle repulsion

A

Two identical particles repelling off each other with a photon exchange particle

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23
Q

What is the Feynman diagram of electron capture

A

Proton + electron , W+ boson, Neutron + electron neutrino

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24
Q

What is the Feynman diagram of beta - decay

A

Neutron , W- boson , Proton + electron + anti electron neutrino

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25
What is the Feynman diagram of beta + decay
Proton, W+ boson, Neutron + positron + electron neutrino
26
What is the Feynman diagram of electron proton collisions
Electron + proton , W- boson, electron neutrino + neutron
27
What is the Feynman diagram of proton-electron attraction
Proton + electron, photon ,Proton + electron
28
What is the Feynman diagram of Neutron neutrino interaction
Neutron + electron neutrino , W- boson, Proton + electron
29
What do bosons do
Converts Neutrons to protons vice versa W+ positrons electron neutrinos W- electrons anti electron neutrinos
30
What is the only stable baryon
Proton
31
What do all baryons decay into
Protons
32
What happens when a neutron decays
Proton + electron + anti electron neutrino
33
What is a lepton
Particle that doesn't feel the strong nuclear force
34
What is the strangeness in a strange quark
-1
35
What can sometimes not be conserved in weak interactions
Strangeness
36
K0 quark config
down, anti strange
37
K+ quark config
up, anti strange
38
K- quark config
strange, anti up
39
K0 _ quark config
strange, anti down
40
Pion - quark config
down, anti up
41
Pion 0 quark config
down, anti down / up, anti up
42
Pion + quark config
up, anti down
43
What needs to be conserved
Charge, Baryon number, lepton number (both electron and muon), strangeness (only in strong)
44
What are photoelectrons released with. Refer to max KE
Varying KE . The value for max KE increases with frequency but unaffected by intensity
45
Why does the photoelectric effect not apply with wave theory
Energy carried is proportional to intensity Energy carried out by light would b e spread out evenly Each electron would gain a bit of energy for every wave until it had enough to leave the surface
46
What does the photoelectric effect support
Einsteins photon model of light
47
When are photoelectrons released
Frequency of the light > Threshold frequency
48
When does light intensity have no effect
When frequency of light < Threshold frequency
49
What is stopping potential
The potential difference needed to stop the fastest moving electrons
50
Stopping potential equations
e x Vs = KE max (1.6x10^-19) x stopping potential = Max KE
51
Explain the graph of I against V for the photoelectric effect
Zero until the stopping potential then proportionally increases until it hits the saturation current then levels out
52
Explain how the photoelectric effect can be seen by using a vacuum photocell
Power supply makes anode +ve relative to cathode, light is shone on cathode, photoelectrons attracted to anode so a complete circuit is made. Photoelectrons are liberated from cathode and travel to anode. Current flows With more +ve voltage, every photoelectron that crosses = maximum current
53
How does increasing light intensity affect a vacuum photocell
More photons a second More photons crossing Bigger current
54
What is the equipment in a vacuum photocell
Anode/Cathode Evacuated Chamber Sensitive ammeter
55
In a vacuum photocell what happens when the anode is -ve
Photoelectrons do work against voltage to cross gap If electron KE>eV can electrons cross gap If V increases eventually no electrons can cross and current = 0A (Stopping potential)
56
Where are electrons in atoms
Discrete energy levels
57
How do electrons move down energy levels
Emitting a photon, only having specific wavelengths
58
What is n=1 state called
Ground
59
What level is the ionisation level and what is ionisation
Zero, energy required to fully remove an electron from ground state
60
What is de-excitation
High---->Low energy level coming with an emission of a photon
61
What is excitation
Low---->High energy levels with absorption of a photon
62
What happens when a high KE electron collides with an atom
Small chance an electron kicks out another electron leaving the ion in the next highest charge state
63
What is inside a gas discharge tube
Two electrodes at either end Pure sample of low pressure vapour of a substance
64
How does a gas discharge tube work
When a high voltage is applied on the electrodes, the gas can conduct electrons. Electrons are accelerated to high speeds towards the +ve electrode The high energy electrons collide with vapour molecules to become excited When vapour molecules de-excite, they emit only specific frequencies of photons
65
What is absorption spectra
When white light passes through a cool gas and refracted off a prism, a spectra of black lines appears on a continuous spectra
66
What is an emission spectra
When whiter light passes through an excited gas and refracted off a prism, a spectra of coloured lines appear on a black background
67
What does absorption and emission spectra show
That each line corresponds to transitions between energy levels
68
Definition of fluorescence
The absorption of light outside the visible spectrum and re-emitting the light in the visible spectrum
69
Explain how fluorescent tube works
Pass a high current through the metal filament heat it Hot enough so that electrons leave the metal surface Thermionic emission at hot cathode generates free electrons which are accelerated towards the anode gaining KE High energy electrons collide with mercury atoms exciting them The mercury atoms de-excite emitting UV photons Fluorescent coating made of phosphor atoms absorb the UV photons becoming excited The atoms de-excite emitting visible photons
70
Pros/Cons of fluorescent lights
P -Cheaper/Produce less waste/Much brighter C -Lots of energy/Really hot/Mercury/Flicker
71
How do waves show wave-particle duality
Shows light with interference and diffraction
72
How do particles show wave-particle duality
Shows light with photoelectric effect
73
What is the wave-particle theory
If 'wave like' light showed particle properties (photons), 'particles' like electrons should be expected to show wave-like properties
74
What can the de Broglie wavelength be interpreted as
Probability wave
75
Describe the experiment to show electron diffraction
An electron gun shoots electrons at an incredibly small graphite crystal The electrons scatter in the evacuated chamber into green rings showing interference on the phosphor screen

Physics (12 decks)

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