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GCSE Physics > Radioactivity > Flashcards

Radioactivity Flashcards

1
Q

3 types of radiation

A

Alpha
Beta
Gamma

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2
Q

What is irradiation

A

Being exposed to ionising radiation

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3
Q

What is contamination

A

Unwanted presence of radioactive nuclei on/ inside body

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4
Q

What does radiation dose measure

A

The health risk of exposure to radiation. Depends on type and amount of radiation

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5
Q

What does radiation dose depend on

A

Amount and type of radiation

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6
Q

Facts about alpha radiation

A

2 protons, 2 neutrons
Charge of +2
High ionising power
Can be blocked/ absorbed by paper and dead skin cells
Can travel a few cm in air
Away from you isn’t dangerous (doesn’t travel far and can be blocked by skin)
Inside you is dangerous due to high ionising power
Alpha decay occurs when a particle with 2 protons and 2 neutrons (helium nucleus) is released from the nucleus

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7
Q

Facts about beta radiation

A

1 electron
Charge of -1
Can travel a few metres in air
Blocked/ absorbed by a few mm of aluminium
Medium ionising power
Beta decay occurs when a neutron turns into a proton which creates an electron that’s emitted from the nucleus

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8
Q

Facts about gamma radiation

A

It is an electromagnetic wave
It has no charge
It can travel a few km in the air
It can be blocked/ absorbed by a few cm of lead
It has a low ionising power

It is the most dangerous radiation outside of your body because it can travel the furthest and takes a few cm of lead to be blocked but inside of you it’s the least dangerous as it has the lowest ionising power

Gamma decay occurs when the nucleus releases energy in the form of an electromagnetic wave (photon) e.g during nuclear fission process

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9
Q

What is alpha decay

A

Particle with 2 protons and 2 neutrons released from the nucleus
(What’s released is the same as a helium nucleus)

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10
Q

What is beta decay

A

Neutron turns into proton which creates an electron that’s emitted from the nucleus

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11
Q

What is gamma decay

A

Nucleus releases energy in form of electromagnetic wave (photon)

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12
Q

What is the type of electromagnetic wave called in gamma radiation

A

Photon

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13
Q

Which type of radiation is most dangerous inside body

A

Gamma- has highest ionising power

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14
Q

Why is alpha radiation the most dangerous when in the body

A

Has highest ionising power

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15
Q

Why is gamma radiation not very dangerous outside of the body

A

Can only travel a few cm in air
Is blocked by dead skin cells

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16
Q

Which type of radiation is most dangerous outside of body

A

Gamma
Travels a few km in air
Requires a few cm of lead to be blocked

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17
Q

Which type of radiation is least dangerous inside the body

A

Gamma- has lowest ionising power

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18
Q

What can each type of radiation be blocked/ absorbed by

A

Alpha- paper/ dead skin cells
Beta- a few mm of aluminium
Gamma- a few cm of lead

19
Q

What is meant by activity

A

Rate at which source of unstable nuclei decays
(Measured in Bq)

20
Q

What is meant by Count rate

A

Number of decays recorded each second by a detector
(Measured in a Bq)

21
Q

Example of detector used to measure count rate

A

Geiger-Muller tube

22
Q

3 uses of radioactivity

A

Medical traces, automatic thickness monitoring, radiotherapy

23
Q

What is meant by hale life of radioactive isotope

A

Average time for half of unstable nuclei to decay/ for activity of source to half

24
Q

The activity of a radioactive source decreases….

A

Exponentially

25
Q

How can a radioactive substance become more stable

A

Unstable nuclei decay (emit ionising radiation)

26
Q

True or false, background radiation is around us all the time

A

True

27
Q

Examples of background radiation

A

Natural sources- rocks, food, animals, cosmic rays
Man-made sources- nuclear weapons and nuclear accidents

28
Q

Natural sources of background radiation

A

Food, cosmic rays, rocks, animals

29
Q

Manmade sources of background radiation

A

Nuclear weapons and nuclear accidents

30
Q

What is nuclear fusion

A

Joining of 2 smaller atomic nuclei to form 1 larger one
During nuclear fusion some of the mass of the nuclei is converted into energy therefore the larger nuclei has a lower overall mass

31
Q

During nuclear fusion why does the larger nuclei have a lower overall mass

A

During the process some of the mass of the smaller nuclei is converted into energy

32
Q

What is formed from the 2 smaller nuclei in nuclear fusion

A

1 larger nuclei with a lower overall mass (some mass of the smaller ones is converted to energy)

33
Q

What is nuclear fission

A

Splitting of an atomic nucleus
Neutron gets absorbed by a fissionable nucleus, nucleus breaks apart into 2 daughter nuclei and releases 2-3 neutrons + energy in the form of gamma rays

34
Q

Process of nuclear fission

A

Fissionable nucleus absorbs a neutron
Nucleus becomes unstable and splits into 2 daughter nuclei
Energy released in form of gamma rays + 2-3 neutrons released

35
Q

What does a fissionable nucleus absorb in nuclear fission

A

A neutron

36
Q

After 2 daughter nuclei are formed what else is released in nuclear fission

A

2-3 neutrons
Energy in form of gamma rays

37
Q

Do irradiated objects become radioactive

A

No, they are just exposed to the radiation

38
Q

Do contaminated objects become radioactive

A

Yes

39
Q

Which out of contaminated and irradiated objects become radioactive

A

Contaminated

40
Q

Briefly explain how automatic thickness monitoring works (a way of thinning metal to make aluminium foil)

A

Beta radiation is absorbed by the aluminium
Thicker aluminium means more beta radiation absorbed so lower count rate
Thinner aluminium means less beta radiation absorbed so higher count rate
Detector of count rate works out how thin/ thick it is

41
Q

Type of radiation absorbed by aluminium in automatic thickness monitoring process

A

Beta

42
Q

Briefly explain how radiotherapy works

A

Radiation treats tumours by killing targeted cancer cells
Means fired from multiple angles so only target gets high dose

43
Q

Radioactive traces show flow through an..

A

Organ

GCSE Physics (13 decks)

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