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Physics Yr1 > Particles and Radiation > Flashcards

Particles and Radiation Flashcards

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1
Q

How to calculate specific charge and its unit

Define Specific Charge

A

Charge ÷ Mass

Ckg¯¹

Charge per kg of a particle

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2
Q

What is an isotope

A

An atom with the same number of protons but different number of neutrons

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3
Q

In the diagram, what does the 4 represent and the 2 represent

A

4 is the atomic mass - no. of protons + neutrons

2 is the atomic number - number of protons

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4
Q

What is the strong nuclear force, and its graph

A

Force that counteracts the electrostatic force of attraction between protons in the nucleaus, keeping the nucleaus together

Has a range of 3-4 fm

Below 0.5 fm, it acts as a repulsive force to stop nucleons being pushed into each other

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5
Q

When is a nucleaus unstable

A

When it 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.

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6
Q

What is alpha decay

A

Decay of a nucleus when there are too many protons and neutrons

An aplha particle that has 2 protons and 2 neutrons in emitted

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7
Q

What is Beta Minus Decay

A

Decay of a nucleus that has too many neutrons

The neutron turns into a proton which stays in the nucleus

This causes an electron to be emitted as a Beta particle with a neutrino

n → p + e- + νe

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8
Q

What is an antiparticle

A

Has the same rest energy and mass, but all other properties are opposite to its corresponding particle

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9
Q

What is a photon

A

Packet of electromagnetic energy which transfers energy and has no mass

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10
Q

Equation for photon energy

A

E = hf = hc/wavelength

h = Planck constant

c = speed of light

f = frequency

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11
Q

What is annihilation

Give an application of it

A

Where a particle and its corresponding antiparticle collide, as a result their masses are converted into energy. This energy, along with the kinetic energy of the two particles is released in the form of 2 photons moving in opposite directions in order to conserve momentum.

PET scans

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12
Q

What is pair production

A

Where a photon is converted into an 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.

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13
Q

What is a particles rest energy

A

Energy of a particle when it is not moving

K.E is 0

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14
Q

What are the 4 particle interactions, their exchange particles, ranges and what they act on

A

Strong interaction acts on Hadrons

Weak interaction acts on all particles

Electromagnetic Interaction acts on charged particles

Gravity acts on all particles with mass

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15
Q

What is an exchange particle

A

A particle that carries energy and momentum between the particles experiencing the force and each fundamental force has its own exchange particles.

Intercepting it will stop the reaction from happening

It causes the forces between partcles in a reaction

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16
Q

What are the 4 interactions caused by the weak nuclear force

A

Beta Minus Decay

Beta Plus Decay

Electron Capture

Electron proton Collision

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17
Q

Electron Capture

A

p + e − → n + ν(e)

When a nucleus has too many protons, it takes an electron from the atoms inner energy level so it interacts with a proton to produce a neutron and antineutrino

A W^+ Boson is the exchange particle

So the proton loses its positive charge and the electron gains positive charge

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18
Q

Electron - proton Collision

A

p + e − → n + ν(e)

When an electron and proton collide at a high speed, a W¯ Boson will take negative charge from the electron to the proton, producing a neutron and neutrino

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19
Q

Beta Plus Decay

A

A proton in a proton rich nucleus decays into a neutron, emitting a W+ Boson

W+ Boson decays into a positron and neutrino

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20
Q

What is a Lepton

A

Fundamental particle

Not made up of quarks

Interact through all but the Strong Nuclear force

eg. Electron, Muon, Neutrino

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21
Q

What is a Hadron

A

Any particle made up of quarks

Experiences all 4 interactions

22
Q

What is a Baryon

A

Hadron formed of 3 quarks

eg. a Neutron, proton

23
Q

What is a Meson

A

Hadron formed of a quark, antiquark pair

eg. A pion, Kaon

24
Q

What is the only stable Baryon. What does this therefore mean

A

Proton

All Baryons will eventually decay into a proton

25
Q

What is Baryon Number

A

Shows if a particle is a baryon

Baryon = 1

Not a Baryon = 0

Antibaryon = -1

Always conserved

26
Q

What is Lepton Number

A

Shows if a particle is a Lepton

Lepton = 1

Not a Lepton = 0

AntiLepton = -1

Always conserved in interactions

27
Q

What is a Muon

A

A heavy electron

Will eventually decay into an electron

28
Q

What is a strange particle

Give an example of one

A

A particle produced by the strong nuclear interaction but decays by the weak interaction

eg. A Kaon, which decays into a Pion by the weak interaction

Has a strange quark in it

They have strangeness

29
Q

What is strangeness

A

A property of a strange particle

Strange = 1

Not strange = 0

Antistrange = -1

Strangeness can only be changed in a weak interaction

It is conserved in all interactions but weak. So strange particles are produced in pairs

30
Q

What is a quark

A

A fundamental particle that makes up hadrons

31
Q

What is the quark structure of a Proton

A

uud

32
Q

What is the quark structure of a Neutron

A

udd

33
Q

What is conserved in every particle interaction

A

Energy

Momentum

Charge

Baryon No.

Lepton No.

34
Q

What is the Photoelectric Effect

A

The photoelectric effect is where photoelectrons are emitted from the surface of a metal after light above a certain frequency is shone on it.

35
Q

What is Threshold Frequency

A

Minimum frequency of light required to cause the electric effect

36
Q

How does Threshold Frequency show the Wave-Particle Duality of Light

A

If light was a wave, frequency of light should be able to cause photoelectric emission as the energy absorbed by each electron will gradually increase with each incoming wave.

So Threshold Frequency shows that

  • Light travels in Photons
  • Each electron can only absorb 1 photon
  • If the intensity of the light is increased and the frequency is above the threshold, more photoelectrons are emitted per second.
37
Q

What is the work function of a metal

A

the minimum energy required for electrons to be emitted from the surface of a metal.

Denoted by Ø

38
Q

What is stopping potential

A

s the potential difference you would need to apply across the metal to stop the photoelectrons with the maximum kinetic energy.

39
Q

Define light intensity

A

Joules of energy transferred to a surface a photons per second

40
Q

What is excitation

A

Occurs when the energy gained from a collision with a free-electron causes an electron to move up an energy level in an atom

41
Q

What is ionisation

A

Occurs when the electron in the atom gains enough energy from a collision with a free electron to leave the atom.

Will occur if the energy of the free electron is more than the ionisation energy

42
Q

What will usually happen after excitation

A

The electron will return back to its original energy level and release the energy it initially gained in the form of a photon

This is de-excitiation

43
Q

How does a fluorescent tube produce light

A

A p.d is made across the tube that has mercury gas in it, so electrons will accelerate through the tube

As they pass through, they collide with mercury atoms, ionizing them, so they release even more free electrons.

All these free electrons then collide with the mercury atoms, exciting and de-exciting them so photons of UV light are released.

Phosphorous fluorescent coating of the tube absorbs the photons, exciting/de-exciting its electrons so they release photons of visible light

44
Q

Define the electron volt

How do you convert

A

The energy gained by one electron when passing through a potential difference of 1 volt.

1eV = 1.6x10-19J

45
Q

How to produce a line emission spectrum

A

Shine the light produced from a fluorescent tube through a diffraction grating

. Each line in the spectrum will represent a different wavelength of light emitted by the tube.

As this spectrum is not continuous but rather contains only discrete values of wavelengths of photons that diffracted differently

46
Q

What does a line emission spectrum show

A

Different differences of energy between 2 energy levels in an atom

The energy of each photon produced is caused by an electron losing energy by moving between energy levels

The fact that the photons have different energies shows the difference between energy levels is not constant

47
Q

What is a line absorption spectrum

How is it produced

A

A continuous spectrum of all wavelengths of light, but with black lines

When white light passes through a cool gas.

Photons of a certain energy (came from electrons moving between the same 2 energy levels) are all absorbed, leaving no light at that wavelength

48
Q

How is Light shown be a wave

A

Diffraction

Interference

49
Q

How is light shown to be a particle

A

Photoelectric effect

50
Q

How are electrons shown to be a wave

A

Electron diffraction

51
Q

What is the De Broglie Hypothesis

A

The wavelength of a particle is determined by its momentum

De Broglie Wavelength = Planck’s const. ÷ Momentum

52
Q

How is Momentum and amount of diffraction linked

A

A higher momentum decreases a particles De Broglie Wavelength which decreases the amount of diffraction

So the circular diffraction pattern will have a smaller diameter

Physics Yr1 (4 decks)

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