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Physics 101 > Topic 6 - Radioactivity > Flashcards

Topic 6 - Radioactivity Flashcards

1
Q

Background Radiation

A
  • Constant emission of ionising radiation from space and environment
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2
Q

Origins of background radiation in Earth and Space

A
  • Earth : Radon, Foods, X-rays, Gamma-rays, Cancer treatment
  • Space : Cosmic Rays
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3
Q

How to detect radioactivity through Geiger-Muller Tube

A
  • Radiation enter through tube and ionises gases inside, which forms a current to flow, which makes a clicking noise
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4
Q

How to detect radioactivity through Photographic Film

A
  • The ionising radiation causes changes in the crystals in the film that can be seen
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5
Q

How is ionising radiation released?

A
  • Unstable nuclei in a random process
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6
Q

Beta +/- is an electron emitted from the…

A

nucleus

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7
Q

The most ionising decay is…

A

alpha

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8
Q

The most penetrative decay is…

A

gamma

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9
Q

1st atomic model

A

Indivisible mass

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10
Q

2nd atomic model

A

JJ Thompson - Plum Pudding

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11
Q

3rd atomic model

A

Nuclear model

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12
Q

Modern atomic model

A

Bohr model

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13
Q

Beta +/- decay release what electric charges

A

minus = neutrons -> protons + electrons
plus = protons -> neutrons + positron

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14
Q

All nuclear transmission charge and mass numbers

A

Alpha P=-2 M=-4
Beta - P=1 M=0
Beta + P=-1 M=0
Gamma P=0 M=0
Neutron P=0 M=-1

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15
Q

Uses of radiation:

A
  • Smoke alarm
  • Irradiating food
  • Sterilisation of equipment
  • Tracing and gauging thicknesses
  • Diagnosis and treatment of cancer
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16
Q

How do smoke alarms work?

A
  • Smoke enters alarm
  • Breaks circuit formed from radiation
  • Bell rings
17
Q

Precautions taken to ensure safety of people exposed to radiation

A
  • Keep distance
  • Reduce time
  • PPE (e.g. radiation suit)
  • Store underground
18
Q

Contamination

A
  • Unwanted radioactive materials in or on a body
19
Q

Irradiation

A
  • Body exposed to but not physically touching
20
Q

Properties of External Radiation

A
  • Radioactive isotope from machine out of body
  • Very precise
  • Takes many sessions
  • Causes skin irritation, fatigue and damage to nearby tissue
21
Q

Properties of Internal Radiation

A
  • Placed inside or near tumour
  • Better for irregular shaped tumours or tumours in a vital location
  • Short treatment (few sessions)
  • Causes infections and damage to internal organs
22
Q

Uses of radioactive substances in the diagnosis of medical conditions:

A
  • Tracers : Emits radiation, which can be tracked to check if organs are working correctly
  • PET Scanners: Provide detailed three-dimensional images of metabolic activity in tissues
23
Q

Isotopes used in PET scanners have to be produced nearby because:

A
  • Short half-life, so they decay quickly
24
Q

What are the advantages of using nuclear power for electricity generation

A

Nuclear power stations:
- Produce no polluting gases
- Far less fuel required
- Highly reliable

25
Q

What are the disadvantages of using nuclear power for electricity generation

A

Nuclear power stations:
- Produce radioactive waste which is dangerous and expensive to deal with
- Can have catastrophic consequences on the environment and people in the event of a nuclear meltdown
- Expensive start-up and shut down cost

26
Q

Nuclear reactions can be used as:

A
  • a source of energy
27
Q

The products of nuclear fission are all:

A
  • radioactive
28
Q

How fission works:

A
  • Neutron collides with large nucleus
  • Nucleus splits
  • 2 smaller daughter nuclei are released with 2 or more neutrons
  • Gamma rays are emitted (energy released)
29
Q

Principle of a controlled nuclear chain reaction:

A
  • Using nuclear reactions to produce ongoing energy.
30
Q

How is a nuclear chain reaction controlled?

A
  • Neutron Moderator (slows down neutrons)
  • Control Rods (absorbs excess neutrons)
31
Q

Electricity is made from thermal energy from the chain reaction. How?

A
  • Nuclear reactor generates thermal
  • Boiler makes steam with thermal
  • Turbine uses steam to turn thermal to kinetic
  • Generator turns kinetic into electricity
32
Q

What is a star’s energy source?

A
  • Nuclear fusion
33
Q

How fusion works:

A
  • 2 smaller nuclei fuse to create a larger nuclei
  • Results in a loss of mass
  • Process releases energy
34
Q

Nuclear fusion does not happen at low temperatures and pressures because:

A
  • Protons repel and their kinetic energy won’t be high enough
35
Q

The conditions of fusion is difficult to maintain for practical and economic use because:

A
  • Such high temperatures and pressure required for fusion are hard to contain, meaning only a small amount of fusion occurs

Physics 101 (20 decks)

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