Define background radiation .

Background radiation is the radiation that exists around us all the time.

True or False? Radiation is solely a human-made phenomenon.

False. Radiation is a natural phenomenon from radioactive elements that have always existed on Earth and in outer space. Man-made sources from human activity add to the amount of radiation humans are exposed to.

What are the natural sources of background radiation?

Natural sources of background radiation include: radon gas (in the air) rocks and buildings food and drink cosmic rays from space carbon-14 in biological material

True or False? Ionising nuclear radiation can be measured using a detector connected to an emitter.

False. Ionising nuclear radiation can be measured using a detector connected to a counter .

What are the units of count rate?

Count rate is measured in counts per second or counts per minute .

Does the count rate increase or decrease as the detector moves further from the radiation source?

The count rate decreases as the detector moves further from the radiation source. This is because the radiation becomes more spread out the further away it is from the source.

True or False? Nuclear decay is predictable and organised.

False. Nuclear decay is spontaneous and random .

What is the composition of an alpha particle?

An alpha particle is composed of two protons and two neutrons . It is the same as a helium nucleus .

What is the composition of a beta particle?

A beta particle is a fast-moving electron . Beta particles are produced in nuclei when a neutron changes into a proton and an electron .

What is the nature of gamma radiation?

Gamma radiation is an electromagnetic wave . Gamma rays have the highest energy of the different types of electromagnetic waves and have no charge .

True or False? Alpha particles have a charge of −1.

False. Alpha particles have a charge of +2 due to having two positively charged protons . It is beta particles that have a charge of −1 due to the negatively charged electron .

Which type of nuclear radiation is the most ionising?

Alpha particles are the most ionising form of nuclear radiation. Beta particles are moderately ionising, and gamma radiation is the least ionising.

What are the types of nuclear radiation in order of increasing penetrating power?

The types of nuclear radiation in order of increasing penetrating power are: alpha ( least penetrating, stopped by a thin sheet of paper ) beta (stopped by a few mm of aluminium ) gamma ( most penetrating, only reduced by a few cm of lead )

Which types of nuclear decay cause the isotope to decay into a new element?

An isotope will decay into a new element if the number of protons changes. Therefore, alpha and beta decay will produce a new element.

Define daughter nucleus .

The daughter nucleus is the nucleus of the new element produced during radioactive decay. The initial nucleus is called the parent nucleus .

By what value does the mass number decrease as a result of alpha decay?

Alpha decay results in the mass number decreasing by 4 , because 4 nucleons (2 protons and 2 neutrons) are emitted.

By what value does the atomic number decrease as a result of alpha decay?

Alpha decay results in the atomic number decreasing by 2 , because 2 protons are emitted.

By what value does the charge on a nucleus decrease when it emits an alpha particle?

The charge on a nucleus will decrease by 2 after it emits an alpha particle, because 2 protons are emitted and protons have a charge of +1 each.

True or False? In beta decay, a neutron changes into a proton and an electron.

True. A neutron changes into a proton and an electron during beta decay. The high-energy electron is emitted and the proton remains in the nucleus.

By what value does the atomic number change as a result of beta decay?

The atomic number increases by 1 as a result of beta decay, so a new element is formed.

How is the mass number affected by beta decay?

The mass number remains unchanged by beta decay. A neutron changes into a proton, which has the same mass number. A beta particle is emitted, but its mass is negligible.

How are the mass and atomic numbers affected by gamma decay?

Gamma decay has no effect on the mass number or the atomic number . Gamma radiation makes the nucleus less energetic but does not change its structure, because gamma radiation has no mass or charge.

In a decay equation, what must be true of the mass and atomic numbers before and after the decay? (Extended Tier Only)

The sum of the mass numbers and the sum of the atomic numbers before the decay must be the same as the sums after the decay.

Define the term half-life .

Half-life is the time taken for half the nuclei of a particular isotope in any sample to decay .

True or False? The half-life for a particular isotope is always the same.

True. Half-life is constant for any particular isotope.

How is the activity of a radioactive sample affected after one half-life?

The activity of a radioactive sample will have halved after one half-life.

True or False? Half-life is different for different isotopes.

True. Half-life is different for different isotopes, and can vary from a fraction of a second to billions of years.

How do you determine the half-life of an isotope on a graph of activity over time?

To determine the half-life of an isotope on a graph of activity over time: identify the point at which the activity has halved and draw a line to the curve track that point down to the time axis

Which type of nuclear radiation is used in smoke detectors?

Alpha radiation is used in smoke detectors.

Which type of nuclear radiation is used for measuring and controlling the thickness of materials?

Beta radiation is used in measuring and controlling the thickness of materials.

Which type of nuclear radiation is used for irradiating food to kill bacteria?

Gamma radiation is used for irradiating food to kill bacteria.

Which type of nuclear radiation is used for sterilising equipment?

Gamma radiation is used for sterilising equipment.

How does a smoke alarm work?

A smoke alarm works as follows: alpha particles ionise the air inside the detector creating a current the alpha emitter is blocked by the presence of smoke particles the alarm is triggered when the sensor no longer detects alpha particles

Why are alpha particles not used to detect the thickness of materials?

Alpha particles are stopped by paper , so they would not penetrate the material to reach the detector .

Why is gamma radiation used in the sterilisation of food and equipment?

Gamma radiation can penetrate packaging and objects so all surfaces of the food or equipment can be irradiated . Gamma radiation is ionising enough to kill any microorganism , therefore it is used for sterilisation.

Why are beta particles used to detect the thickness of materials?

Beta particles can penetrate materials such as paper and aluminium foil, so the number of beta particles detected by a sensor can be used to measure and control the thickness of the substance.

How is gamma radiation used in the treatment of cancer?

Gamma radiation is used in the treatment of cancer in the process of radiotherapy. Gamma radiation can damage cells and tissues so this can be used to target cancer cells. Gamma rays can penetrate the body to reach the cancer cells, but the beams must be emitted from different angles to reduce the damage to healthy tissues.

What are the three effects of ionising nuclear radiation on living things?

The three effects of ionising nuclear radiation on living things are: cell death mutations cancer

How does ionising radiation cause cell mutations?

Ionising radiation can remove electrons from the atoms that make up DNA and therefore change the structure of the molecule. A structural change in DNA can lead to mutated cells. Mutated cells usually either die or get destroyed by the immune system, but some mutations can cause cells to replicate uncontrollably and lead to cancer .

What could over-exposure to nuclear radiation lead to?

Over-exposure to nuclear radiation could lead to acute radiation poisoning .

What three safety precautions reduce the dangers of ionising radiation?

Safety precautions for all ionising radiation include: reducing exposure time increasing the distance between the source and living tissue using shielding to absorb radiation

How should radioactive samples be handled?

Radioactive samples should be handled by: storing the sample encased in lead using tongs to move the sample wearing protective clothing, such as a lead apron keeping the sample at a distance from the body minimising the exposure time

Define the term dose in relation to radioactive substances.

A dose is the amount of radiation received by a person. It is measured in sieverts (Sv).

IGCSEScienceCambridge (CIE)Co-ordinated Sciences (Double Award)PhysicsFlashcards5. Nuclear PhysicsRadioactivity

Radioactivity (Cambridge (CIE) IGCSE Co-ordinated Sciences (Double Award): Physics): Flashcards

Exam code: 0654 & 0973

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FrontIonising Nuclear & Background Radiation
Define background radiation.
FrontIonising Nuclear & Background Radiation
What are the natural sources of background radiation?
BackIonising Nuclear & Background Radiation
Natural sources of background radiation include:
radon gas (in the air)
rocks and buildings
food and drink
cosmic rays from space
carbon-14 in biological material

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Cards in this collection (47)

Define background radiation.
Background radiation is the radiation that exists around us all the time.
True or False?
Radiation is solely a human-made phenomenon.
False.
Radiation is a natural phenomenon from radioactive elements that have always existed on Earth and in outer space. Man-made sources from human activity add to the amount of radiation humans are exposed to.
What are the natural sources of background radiation?
Natural sources of background radiation include:
- radon gas (in the air)
- rocks and buildings
- food and drink
- cosmic rays from space
- carbon-14 in biological material
True or False?
Ionising nuclear radiation can be measured using a detector connected to an emitter.
False.
Ionising nuclear radiation can be measured using a detector connected to a counter.
What are the units of count rate?
Count rate is measured in counts per second or counts per minute.
Does the count rate increase or decrease as the detector moves further from the radiation source?
The count rate decreases as the detector moves further from the radiation source. This is because the radiation becomes more spread out the further away it is from the source.
What are the three types of radiation that an unstable nucleus can emit?
The three types of radiation that an unstable nucleus can emit are:
- alpha ( $α$ ) particles
- beta ( $β^{-}$ ) particles
- gamma ( $γ$ ) radiation
True or False?
Nuclear decay is predictable and organised.
False.
Nuclear decay is spontaneous and random.
What is the composition of an alpha particle?
An alpha particle is composed of two protons and two neutrons. It is the same as a helium nucleus.
What is the composition of a beta particle?
A beta particle is a fast-moving electron. Beta particles are produced in nuclei when a neutron changes into a proton and an electron.
What is the nature of gamma radiation?
Gamma radiation is an electromagnetic wave. Gamma rays have the highest energy of the different types of electromagnetic waves and have no charge.
True or False?
Alpha particles have a charge of −1.
False.
Alpha particles have a charge of +2 due to having two positively charged protons. It is beta particles that have a charge of −1 due to the negatively charged electron.
Which type of nuclear radiation is the most ionising?
Alpha particles are the most ionising form of nuclear radiation. Beta particles are moderately ionising, and gamma radiation is the least ionising.
What are the types of nuclear radiation in order of increasing penetrating power?
The types of nuclear radiation in order of increasing penetrating power are:
- alpha (least penetrating, stopped by a thin sheet of paper)
- beta (stopped by a few mm of aluminium)
- gamma (most penetrating, only reduced by a few cm of lead)
Which types of nuclear decay cause the isotope to decay into a new element?
An isotope will decay into a new element if the number of protons changes. Therefore, alpha and beta decay will produce a new element.
Define daughter nucleus.
The daughter nucleus is the nucleus of the new element produced during radioactive decay. The initial nucleus is called the parent nucleus.
By what value does the mass number decrease as a result of alpha decay?
Alpha decay results in the mass number decreasing by 4, because 4 nucleons (2 protons and 2 neutrons) are emitted.
By what value does the atomic number decrease as a result of alpha decay?
Alpha decay results in the atomic number decreasing by 2, because 2 protons are emitted.
By what value does the charge on a nucleus decrease when it emits an alpha particle?
The charge on a nucleus will decrease by 2 after it emits an alpha particle, because 2 protons are emitted and protons have a charge of +1 each.
True or False?
In beta decay, a neutron changes into a proton and an electron.
True.
A neutron changes into a proton and an electron during beta decay. The high-energy electron is emitted and the proton remains in the nucleus.
By what value does the atomic number change as a result of beta decay?
The atomic number increases by 1 as a result of beta decay, so a new element is formed.
How is the mass number affected by beta decay?
The mass number remains unchanged by beta decay. A neutron changes into a proton, which has the same mass number. A beta particle is emitted, but its mass is negligible.
How are the mass and atomic numbers affected by gamma decay?
Gamma decay has no effect on the mass number or the atomic number. Gamma radiation makes the nucleus less energetic but does not change its structure, because gamma radiation has no mass or charge.
In a decay equation, what must be true of the mass and atomic numbers before and after the decay? (Extended Tier Only)
The sum of the mass numbers and the sum of the atomic numbers before the decay must be the same as the sums after the decay.
What is the general form of an alpha decay equation for isotopes X and Y? (Extended Tier Only)
All alpha decay equations have the form:
$_Z^{A} X \to_{Z - 2}^{A - 4} Y +_2^{4} α$
Define the term half-life.
Half-life is the time taken for half the nuclei of a particular isotope in any sample to decay.
True or False?
The half-life for a particular isotope is always the same.
True.
Half-life is constant for any particular isotope.
How is the activity of a radioactive sample affected after one half-life?
The activity of a radioactive sample will have halved after one half-life.
True or False?
Half-life is different for different isotopes.
True.
Half-life is different for different isotopes, and can vary from a fraction of a second to billions of years.
What is the value of the activity of a radioactive sample after two half-lives?
The value of the activity of a radioactive sample after two half-lives is $\frac{1}{4}$ of its original value.
How do you determine the half-life of an isotope on a graph of activity over time?
To determine the half-life of an isotope on a graph of activity over time:
- identify the point at which the activity has halved and draw a line to the curve
- track that point down to the time axis
What proportion of original nuclei in a radioactive sample will remain after three half-lives?
After three half-lives, the proportion of original nuclei remaining in the sample will be $\frac{1}{8}$ .
Which type of nuclear radiation is used in smoke detectors?
Alpha radiation is used in smoke detectors.
Which type of nuclear radiation is used for measuring and controlling the thickness of materials?
Beta radiation is used in measuring and controlling the thickness of materials.
Which type of nuclear radiation is used for irradiating food to kill bacteria?
Gamma radiation is used for irradiating food to kill bacteria.
Which type of nuclear radiation is used for sterilising equipment?
Gamma radiation is used for sterilising equipment.
How does a smoke alarm work?
A smoke alarm works as follows:
- alpha particles ionise the air inside the detector creating a current
- the alpha emitter is blocked by the presence of smoke particles
- the alarm is triggered when the sensor no longer detects alpha particles
Why are alpha particles not used to detect the thickness of materials?
Alpha particles are stopped by paper, so they would not penetrate the material to reach the detector.
Why is gamma radiation used in the sterilisation of food and equipment?
Gamma radiation can penetrate packaging and objects so all surfaces of the food or equipment can be irradiated. Gamma radiation is ionising enough to kill any microorganism, therefore it is used for sterilisation.
Why are beta particles used to detect the thickness of materials?
Beta particles can penetrate materials such as paper and aluminium foil, so the number of beta particles detected by a sensor can be used to measure and control the thickness of the substance.
How is gamma radiation used in the treatment of cancer?
Gamma radiation is used in the treatment of cancer in the process of radiotherapy. Gamma radiation can damage cells and tissues so this can be used to target cancer cells. Gamma rays can penetrate the body to reach the cancer cells, but the beams must be emitted from different angles to reduce the damage to healthy tissues.
What are the three effects of ionising nuclear radiation on living things?
The three effects of ionising nuclear radiation on living things are:
- cell death
- mutations
- cancer
How does ionising radiation cause cell mutations?
Ionising radiation can remove electrons from the atoms that make up DNA and therefore change the structure of the molecule. A structural change in DNA can lead to mutated cells. Mutated cells usually either die or get destroyed by the immune system, but some mutations can cause cells to replicate uncontrollably and lead to cancer.
What could over-exposure to nuclear radiation lead to?
Over-exposure to nuclear radiation could lead to acute radiation poisoning.
What three safety precautions reduce the dangers of ionising radiation?
Safety precautions for all ionising radiation include:
- reducing exposure time
- increasing the distance between the source and living tissue
- using shielding to absorb radiation
How should radioactive samples be handled?
Radioactive samples should be handled by:
- storing the sample encased in lead
- using tongs to move the sample
- wearing protective clothing, such as a lead apron
- keeping the sample at a distance from the body
- minimising the exposure time
Define the term dose in relation to radioactive substances.
A dose is the amount of radiation received by a person. It is measured in sieverts (Sv).

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