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IGCSE PHYSICS > Radiation > Flashcards

Radiation Flashcards

1
Q

Give 3 examples of background radiation

A

radon in air (50%)
rocks and building
foods like bananas
Cosmic rays

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2
Q

Why might an unstable nucleus decay to become more stable?

A

As the radiation moves away from the nucleus, it takes some energy with it

This makes the nucleus more stable

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3
Q

what is radioactive decay?

A

The process of emitting particles or waves of energy from an unstable nuclei

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4
Q

why might isotopes be unstable?

A

too many or too few neutrons

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5
Q

why is alpha radiation the most ionising?

A

they are the heaviest

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6
Q

which type of radiation is most penetrating?

A

gamma

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7
Q

which radiation has the most penetrating power?

A

gamma

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8
Q

what type of particle is beta?

A

high energy electron

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9
Q

before doing an experiment with geiger counter, what must you do first?

A

measure back ground rate three times, and subtract the average from all the readings you will take during the experiment.

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10
Q

how would i measure penetrating powers of radioactive sources?

A

use geiger counter and absorbers at a set distance ( absorbers like lead, aluminium, paper)

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11
Q

what happens during alpha decay?

A

alpha particle (2 protons 2 neutrons) emitted from parent nucleus, and a complete new element is formed in the process (daughter nucleus)

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12
Q

What happens during beta decay?

A

A neutron is converted into a proton and electron. Proton stays in the nuclei but electron is emitted.

often happens when unstable nuclei that have too many neutrons

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13
Q

what happens during gamma decay?

A

a gamma ray is emitted from an unstable nucleus

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14
Q

what effect does gamma decay have on the unstable nucleus?

A

the nucleus becomes less energetic but the structure stay the same.

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15
Q

what is neutron emission?

A

a type of radioactive decay that happens to a small number of isotopes.

happens when isotopes emit neutrons. top number decreases by one.

doesn’t form a completely new element like alpha, instead just forms an isotope cuz remember isotopes are same no. of protons and electrons but diff no of neutrons

in the equation you would just add +1 over 0 n

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16
Q

artificial sources of background radiation

A

x-rays, medical tracers, nuclear accidents (chernobyl), nuclear weapon residue

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17
Q

The activity of a radioactive source is defined as:

A

The rate at which the unstable nuclei decay

Activity is measured in becquerels (Bq) per second

eg- 9000 Bq means 9000 unstable nuclei decay per second.

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18
Q

what is a count rate?

A

count rate is the rate at which radioactive emissions are detected.

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19
Q

what type of radiation is used in smoke detectors? how?

A

alpha particles.

When no smoke is present, alpha particles ionise the air and cause a current to flow. When smoke is present, alpha particles are absorbed and current is prevented from flowing which triggers the alarm

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20
Q

what radiation is used to maintain thickness of material.

A

beta, cuz alpha would be absorbed or “stopped” by all thicknesses and gamma would be stopped by none.

If the material gets thicker, more particles will be absorbed “stopped”, and the count rate will decrease. It will cause rollers to push closer together to make the material thinner.

If the material gets thinner, fewer particles will be absorbed “stopped”, and the count rate will increase, causing rollers to move further apart.

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21
Q

how is gamma used in treating cancer/medically?

A

it is ionising and can penetrate tissues. so, gamma ray will be targeted at a tumor in the body from multiple angles to minimise risk of harming healthy tissue and will ionise tumor, trying to kill the cells. known as radiotherapy.

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22
Q

why is gamma most suitable for sterilising medical equipment?

A

It is the most penetrating out of all the types of radiation

It is penetrating enough to irradiate all sides of the instruments

Instruments can be sterilised without removing the packaging

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23
Q

anyone working with radiation can do what as precautions?

A

wear radiation badge

minimise exposure

store in a lead-lined container

use short half-life isotopes

24
Q

each half life decreases (___ ___) by half.

A

count rate

25
why is radon gas in air a greater risk than solid americum in a smoke detector?
range of alpha radiation is low radon is a gas so particles are mobile americum is solid and stays inside detector radon can be inhaled
26
what does irradiation mean, and why might we do it?
The process of exposing a material to ionising radiation to remove live cells to prevent contamination Food can be irradiated to kill any micro-organisms within it to make it last longer
27
Summarise the difference in the risk posed by radioactive sources with very short and very long half-lives in regard to (a) irradiation (b) contamination.
Irradiation poses a greater risk in sources with... Shorter half-lives, cz that means a source has a high activity, therefore high rate of radioactive emissions, compared to a source with a long half-life (b) Contamination poses a greater risk in sources with... Longer half-lives, cz they will remain radioactive for longer They need to be controlled for longer, to prevent them spreading Shielding and storage may be required
28
what is contamination?
the unwanted presence of radioactive isotopes in or on other materials.
29
how can radiation cause dna mutation?
it enters nucleus of a human cell, causinf dna to break. Sometimes the cell can successfully repair the DNA, but incorrect repairs can cause a mutation.
30
31
What is a risk associated with sources that have long half-lives?
Contamination for a much longer time ## Footnote Long half-lives can result in prolonged hazards from radioactive waste.
32
How can radioactive waste with a long half-life be managed?
Buried underground to prevent release into the environment ## Footnote This method aims to isolate the waste from the biosphere.
33
What is a requirement for storing radioactive waste?
Strong containers ## Footnote These containers are necessary to prevent the release of radioactive materials.
34
What must containers for radioactive waste be able to withstand?
Harsh conditions over long periods ## Footnote This ensures the integrity of the waste containment.
35
What specific resistance must containers for radioactive waste have?
Resist rust and corrosion ## Footnote This is critical to prevent degradation of the containers.
36
What is a challenge associated with rust-proof containers?
Expensive and challenging to manufacture ## Footnote The cost and complexity can impact waste management strategies.
37
What type of security must a disposal site for radioactive waste have?
High security to prevent unauthorized access ## Footnote Ensuring security is essential to protect public safety.
38
What is an important geological consideration for a disposal site?
Low risk of natural disasters, e.g. earthquakes ## Footnote This minimizes the chance of containment failure due to geological events.
39
What can help prevent radioactive waste from leaking into groundwater?
Careful site selection and strong containers ## Footnote Both factors are critical in waste management strategies.
40
How can radioactive waste be diluted to minimize concentration?
In large volumes of seawater ## Footnote This method helps reduce the potential impact of radioactive materials.
41
what are three sources of nuclear energy?
Nuclear fusion Nuclear fission Radioactive decay
42
43
What must an unstable nucleus absorb for fission to occur?
A neutron ## Footnote This absorption increases the instability of the nucleus.
44
What happens to the nucleus after it absorbs a neutron?
It decays almost immediately ## Footnote This decay is a result of the increased instability of the nucleus.
45
What is the term for fission that occurs when a nucleus absorbs a neutron?
Induced fission ## Footnote Induced fission is a specific type of nuclear fission triggered by neutron absorption.
46
what can we tell about an isotope that has a very long half life?
it has low activity and releases energy very slowly
47
what are products of fission?
During fission, when a neutron collides with an unstable nucleus, the nucleus splits into two smaller nuclei (daughter nuclei) two or three neutrons gamma rays are also emitted
48
why do the products of the fission reaction move away very quickly?
This is because energy is transferred from the nuclear potential energy stored in the original nucleus into the kinetic energy of the products In a nuclear power station, this energy can be harnessed and converted into electrical energy
49
what is a chain reaction?
when a neutron emitted from the splitting of a nucleus causes further nuclei to split and the neutrons emitted from these cause further fission reactions
50
what is the purpose of a nuclear reactor?
to control chain reactions and collect the heat energy produced from nuclear reactions to generate electricity
51
what is purpose of control rods and what is it usually made out of?
to absorb neutrons without becoming unstable themselves, and control rate of fission. Control number of free neutrons Lowering the rods further decreases the rate of fission, as more neutrons are absorbed Raising the rods increases the rate of fission, as fewer neutrons are absorbed rods can be lowered fully to completely stop rate of fission. usually made of boron
52
What is purpose of moderator? what is it usually made of?
to slow neutrons down. fast-moving neutrons produced by the fission reactions slow down by colliding with the molecules of the moderator, causing them to lose some momentum. usually made of graphite.
53
what is purpose of shielding? what is it usually made of?
The daughter nuclei formed during fission, and the neutrons emitted, are radioactive The reactor is surrounded by a steel and concrete wall This absorbs the emissions from the reactions and ensures that the environment around the reactor is safe for workers
54
when fusion reactors will be commercially developed to generate electricity, what advantages would it have over fission reactors?
Nuclear fusion reactions are capable of generating more energy than fission reactions The nuclear fuel required for fusion (isotopes of hydrogen found in water) is more abundant than the fuel required for fission (uranium and plutonium) Nuclear fusion produces no long-lived nuclear waste products (produces big nuclei which are stable and not radioactive unlike fission)
55
what are two conditions of fusion and why are they so high?
extremely high temperatures and pressures, because of the electrostatic repulsion between protons Since protons have a positive charge, they repel each other Therefore, to overcome this repulsion, protons must have very high kinetic energies to allow them to get close enough to fuse
56

IGCSE PHYSICS (8 decks)

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