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Physics > Paper 1 - Radioactivity And Particles > Flashcards

Paper 1 - Radioactivity And Particles Flashcards

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1
Q

What is the definition of Half-Life?

A

The time it takes for the count rate of a radioactive source to fall to half its original count rate

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2
Q

Describe the nature of alpha particles

A
  • Stopped my air or paper
  • Stronger affected by magnetic fields
  • Heaviest particle
  • Heavily charged
  • Least penetrating power
  • Most ionising
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3
Q

What is meant by atomic number?

A

The number of protons in the nucleus

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4
Q

Describe uses of radioactivity in medicine

A
  • Gamma rays used to sterilise medical equipment
  • Gamma rays can be used to target and destroy cancer cells
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5
Q

What happens to a radioactive source over time?

A

Activity (measured in Becquerels) decreases over time

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6
Q

What is meant by mass number?

A

The sum of the number of protons and neutrons in a nucleus

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7
Q

Describe the effects of neutron emission on the atomic and mass numbers of an atom

A
  • Atomic number : no change
  • Mass number : decreases by 1
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8
Q

Describe the structure of an atom in terms of protons, neutrons and electrons

A
  • An atom has a nucleus containing protons and neutrons with an overall positive charge
  • And gas orbital electrons, surrounding the nucleus in shells
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9
Q

What is background radiation?

A
  • Radiation that is all around us at all times at a safe level
  • Measured in Becquerels
  • Includes alpha, beta and gamma radiation
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10
Q

What are the sources of background radiation and are they natural or artificial?

A
  • Cosmic rays - natural
  • Radon gas - natural
  • Food and drink - artificial
  • Nuclear weapon testing - artificial
  • Nuclear power stations - artificial
  • Medical - artificial
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11
Q

Describe the effects of Gramma emission on the atomic and mass numbers of an atom

A
  • Atomic number : no change
  • Mass number : no change
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12
Q

What is meant by isotope?

A
  • Same number of protons
  • Different number of neutrons
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13
Q

What can vary between different radioactive isotopes?

A

Half-Life

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14
Q

What is the difference between contamination and irritation?

A
  • contamination is when a non-radioactive object comes into contact with a radioactive material
  • irradiation is when radiation is present
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15
Q

Describe the effects of Beta emission on the atomic and mass numbers of an atom

A
  • Atomic number : Increases by 1
  • Mass number : no change
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16
Q

What are the issues with disposing of radioactive waste?

A
  • Elements like Plutonium and Uranium have incredibly long half-lives and therefore will emit dangerous levels of radiation for a long term
  • Which has an effect on plant and animal life
17
Q

What are the dangers of ionising radiations?

A
  • Radiation can cause mutation in living organisms
  • Radiation can damage cells and tissues
  • There are problems with the disposal of radioactive waste
18
Q

Describe the nature of Gamma particles

A
  • Most penetrative
  • Least ionising
  • Passes through aluminium but not lead
  • Not a particle so has no charge or mass
  • Pure energy
19
Q

Describe uses of radioactivity in industry

A
  • Can be used in smoke detectors
  • Can be used in thickness detectors
  • Can be used for nuclear weapons
  • Can be used for radioactive tracers
  • Can be used for leak detectors
20
Q

What are alpha, beta and gamma rays?

A

Ionising radiations emitted from unstable nuclei in a random process

21
Q

Describe the effects of Alpha emission on the atomic and mass numbers of an atom

A
  • Atomic number - decreases by 2
  • Mass number : decreases by 4
22
Q

Describe the nature of Beta particles

A
  • More penetrative than alpha, less penetrative than gamma
  • Lighter than alpha
  • Negative charge
  • Stopped by aluminium or thin plastic
23
Q

What can photographic film or a Geiger-Muller detector do?

A

Detect ionising radiations

24
Q

What can nuclear reactions including fission and fusion be?

A

Sources of energy

25
Q

How is a nucleus of Uranium-235 split?

A
  • The process of fission
  • Neutron collides with Uranium-235 atomic
  • This releases energy as kinetic energy of the fission products
26
Q

What does the fission of Uranium-235 produce?

A
  • 2 radioactive daughter nuclei
  • A small number of neutrons
27
Q

How can a chain reaction be set up if the neutrons produced by one fission
strike other Uranium-235 nuclei?

A

In fission, a neutron from a previous decay can lead to more and more decays

28
Q

Describe the role played by the control rods and moderator in the fission process

A
  • Control rods soak up excess neutrons, preventing the chain reactions from getting out of control, otherwise, this could lead to a nuclear disaster
  • The moderator functions to slow down the neutrons
29
Q

What is nuclear fusion?

A

The creation of larger nuclei resulting in a loss of mass from smaller nuclei, accompanied by a release of energy

30
Q

What is fusion the energy source for?

A

Stars

31
Q

Explain why nuclear fusion does not happen at low temperatures and pressures, due
to electrostatic repulsion of protons

A
  • At low temperatures/pressures, the positively charged protons will repel from each other
  • When moving slowly, the particles do not have enough kinetic energy to overcome the electrostatic forces of repulsion so cannot fuse
32
Q

Explain the difference between nuclear fusion and nuclear fission

A
  • Fission is a chain reactions, Fusion is not
  • Fusion is the joining of nuclei whereas Fission is the splitting of nuclei
33
Q

What is the role of Shielding around a nuclear reactor?

A

To absorb hazardous radiation (daughter nuclei)

34
Q

What are the products of the fission of uranium nuclei?

A
  • neutrons
  • daughter nuclei
  • thermal energy

Physics (15 decks)

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