Particles And Radiation Flashcards

1
Q

What is the charge of a proton and electron?

A

+ or - 1.60x10^-19

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2
Q

What is the mass of a proton?

A

1.673x10^-27 kg

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3
Q

What is the mass of a neutron?

A

1.675x10^-27 kg

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4
Q

What is specific charge?

A

Charge per unit mass
To work out : Charge(C)/ Mass(kg)

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5
Q

What is an isotope?

A

Atoms of an element with the same number of protons and a different number of neutrons

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6
Q

What is the strong force?

A

A force that acts between nucleons in a nucleus to keep it stable. It is attractive at distances of up to 3fm and repulsive at separations less than 0.5fm

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7
Q

What makes a nucleus unstable?

A

Nuclei which have too many of either protons or neutrons or both

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8
Q

How do nuclei with too many nucleons decay?

A

Alpha decay

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9
Q

How do nuclei with too many neutrons decay?

A

Beta minus decay in which a neutrons decays into a proton by the weak interaction

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10
Q

How was the existence of the neutrino hypothesised?

A

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 the neutrino

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11
Q

What is meant by beta minus decay?

A

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

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12
Q

What occurred when a particle and antiparticle meet?

A

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

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13
Q

What is pair production?

A

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

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14
Q

What is an eV?

A

The amount of energy, that an electron gains when it undergoes a potential difference of 1volt, which is 1.60x10^-19

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15
Q

Name the 4 fundamental forces?

A

•Gravity
•Electromagnetic
•Weak nuclear force
•Strong nuclear force

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16
Q

What is the exchange particle for electromagnetic force?

A

The virtual photon

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17
Q

What are hadrons?

A

A subatomic particle that is made up
Of quarks and experiences the strong nuclear force

18
Q

What is the exchange particle of the weak nucleus force?

A

The W boson ( W+ or W-)

19
Q

When does the weak nuclear interaction occur?

A

When a quark changes into another quark

20
Q

Which properties must be conserved in particle interactions?

A

•Energy
•Charge
•Baryon number
•Lepton number
•Momentum
•Strangeness(only for strong interaction)

21
Q

What are the classes of hadrons?

A

•Baryons(three quarks)
•Mesons(1quark, 1antiquark)

22
Q

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

A

Mesons

23
Q

The pion can be an exchange particle for which force?

A

The strong nuclear force

24
Q

What is the difference between a gluon and a pion?

A

Gluons are only the mediators of strong force between quarks inside protons or neutrons. Pions are actually the mediators between protons and neutrons.

25
Q

What is a kaon made up of?

A

1 up quark, 1 down quark and 1 strange quark

26
Q

What particle does a kaon decay into?

A

A kaon decays into a pion

27
Q

What are baryons?

A

They are heavy subatomic particles that are made up of three quarks

28
Q

Give some example of baryons?

A

•Proton - uud
•Neutron - ddu

29
Q

What is a significant about a proton?

A

*It is the only stable baryon
*All baryons will eventually turn into protons

30
Q

What are some examples of leptons?

A

•Electrons
•Muon
•Neutrino
•the antiparticles of the above

31
Q

What does a muon decay into?

A

An electron

32
Q

What is the strangeness value of a strange quark?

A

-1

33
Q

Complete the sentence:
Strange particles are produced through__________ and decay through __________.

A

•Strong interaction
•Weak interaction

34
Q

When does photoelectric emission take place?

A

When the frequency of the electromagnetic radiation is above the threshold frequency

35
Q

What can the wave theory of light not explain?

A

•the existence of the threshold frequency
•why photoelectric emission occurs without delay

36
Q

What did Einstein assume?

A

That light is composed of wave packets (or photons)

37
Q

Give the equation for the energy of a photon

A

Energy of photon = h x f

38
Q

When can an electron leave a metal’s surface?

A

•If the energy gained from a single photon exceeds the work function of the metal
•This is the minimum energy needed by an electron to escape from the metal surface

39
Q

What is the excess energy of the photoelectron turned into?

A

Kinetic energy

40
Q

What is a photoelectron?

A

An electron emitted from a substance due to the photoelectric effect

41
Q

What is the equation for the maximum kinetic energy of an emitted electron?

A

Ekmax =hf - Φ

42
Q

What is the stopping potential?

A

The minimum potential needed to stop photoelectric emission