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GCSE Physics > 7 - Radiation > Flashcards

7 - Radiation Flashcards

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1
Q

What can unstable nuclei emit?

A

Radiation to become more stable

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2
Q

How do unstable nuclei decay?

A

By emitting high energy particles or waves

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3
Q

Why type of process is radioactive decay?

A

Random

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4
Q

What charge do alpha particles have?

A

+2

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5
Q

What can alpha particles be affected by?

A

An electric field

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6
Q

When are beta particles produced in nuclei?

A

When a neutron changes into a proton and an electron

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7
Q

What charge do beta particles have ?

A

-1

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8
Q

Which type of electromagnetic wave has the highest energy?

A

Gamma rays

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9
Q

What is the charge on gamma rays ?

A

No charge

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10
Q

What is alpha stopped by?

A

Paper

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11
Q

What is beta stopped by?

A

A few millimetres of aluminium

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12
Q

What can gamma rays be partially stopped by?

A

Thick lead

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13
Q

What can gamma pass through?

A

Paper + aluminium

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14
Q

What does ionising do to an atom?

A

Gives it a non-zero charge

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15
Q

What is the most ionising form of radiation?

A

Alpha

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16
Q

What is the least ionising form of radiation?

A

Gamma

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17
Q

What happens when a nucleus emits a neutron ?

A
  • total number of particles in nucleus decreases by 1

- the mass number decreases by 1

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18
Q

What can radiation be measured and detected by?

A

A Geiger-Muller tube

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19
Q

What is activity ?

A

The rate at which the unstable nuclei from a source of radiation decays

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20
Q

What happens to the activity of a source with time?

A

It decreases

21
Q

What is half life?

A

The time taken for the activity of a sample to fall to half its original level

22
Q

Gives examples of uses of radioactivity?

A
  • smoke detectors
  • sterilising medical equipment
  • cancer treatment
23
Q

What can beta particles be used for?

A

To measure the thickness of thin materials eg paper, cardboard

24
Q

What can gamma particles be used for?

A

Radiotherapy + sterilising food

25
Q

When does contamination occur?

A

When a radioactive isotope gets onto a material where it should not be

26
Q

What is irradiation ?

A

The process of exposing a material to alpha, beta or gamma radiation

27
Q

What does contamination cause the material to become?

A

Radioactive

28
Q

What does irradiation cause the material to become?

A

NOT radioactive, however can kill living cells

29
Q

How can you protect against radiation?

A
  • protective clothing

- shielded container

30
Q

What is fusion?

A

When 2 small nuclei join together to produce a larger nucleus

31
Q

What is fission?

A

One large nucleus splits into 2 smaller nuclei

32
Q

What is nuclear fission?

A

The splitting of a large unstable nucleus into 2 smaller nuclei

33
Q

Which isotopes undergo fission and are used in nuclear power stations?

A

Uranium + plutonium

34
Q

What is spontaneous fission?

A

When a nuclei undergoes fission without additional energy being put into the nucleus

35
Q

How does fission normally occur?

A

The unstable nucleus must first absorb a neutron

36
Q

What happens during the induced fission of uranium-235?

A

A neutron is absorbed by the uranium-235 nucleus to make uranium-236

37
Q

What are the products of fission?

A
  • gamma rays
  • 2 daughter nuclei
  • 2 or 3 neutrons
38
Q

Describe a chain reaction

A

when a neutron splits a nucleus, releasing more neutrons, which go on to split even more nuclei

39
Q

What are control rods used for + made of ?

A

Boron- To absorb neutrons

40
Q

What does lowering the control rods do?

A

Decreases rate of fission - more neutrons absorbed

41
Q

What does raising the control rods do?

A

Increases rate of fission - fewer neutrons absorbed

42
Q

What is a moderator made of + used for ?

A

Graphite - To slow down neutrons

43
Q

What is the nuclear reactor surrounded with?

A

Shielding materials

44
Q

What is the purpose of shielding ?

A

To absorb hazardous radiation

45
Q

What keeps a nuclear reactor running ?

A

A chain reaction

46
Q

What 2 factors must be controlled when a rector is producing energy at the correct rate?

A
  • number of free neutrons in reactor

- energy of the free neutrons

47
Q

What is nuclear fusion?

A

When 2 light nuclei join to form a heavier nucleus

48
Q

What are the conditions for fusion?

A
  • very high temperature of fuel
  • very high kinetic energy
  • very high density/pressure
49
Q

Why can fusion not take place at a low temperature/low pressure

A

Positively charged nuclei need to be close to fuse, therefore need to be moving very fast to overcome the strong force due to electrostatic repulsion.

GCSE Physics (6 decks)

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