Hazards & Uses of Radioactive Emissions & of Background Radiation (AQA GCSE Physics): Flashcards
Exam code: 8463
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- FrontBackground Radiation
Define background radiation.
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Cards in this collection (23)
Define background radiation.
Background radiation is the radiation that exists around us all the time.
Give two natural sources of background radiation.
Rocks and cosmic rays from space.
Give two man-made sources of background radiation.
Fallout from nuclear weapons testing, and nuclear accidents.
When a radiation source is moved far enough away, the only radiation detected is ______ radiation.
When a radiation source is moved far enough away, the only radiation detected is background radiation.
Define dose (of radiation).
The amount of radiation received by a person, indicating the risk of harm from the exposure.
True or False?
Becquerels, counts per second, and sieverts all measure the same thing.
False.
Becquerels measure the amount of radiation emitted by a source every second, counts per second measures the rate at which radiation hits a location, and sieverts measure the received dose of radiation.
Define half-life.
The time it takes for the activity of a radioactive source to decrease to half of its original value.
Why can a large amount of a short half-life isotope be extremely dangerous to handle?
It decays quickly, emitting a lot of radiation in a short amount of time.
Why is it advantageous to use a small amount of a short half-life isotope?
The material will quickly lose its radioactivity.
Why do sources with a long half-life present a risk of contamination for a long time?
They remain radioactive for a very long time, even though they may not emit much radiation at any one moment.
Radioactive waste with a long half-life is buried ______ to prevent it from being released into the environment.
Radioactive waste with a long half-life is buried underground to prevent it from being released into the environment.
True or False?
The mass of a radioactive sample decreases significantly with each decay.
False.
When an atom decays it changes into another element; it doesn't disappear. The mass only decreases slightly, and only for alpha decay.
Does a substance with a short half-life release more radiation per decay than a substance with a long half-life?
No. If other factors are equal, the amount of radiation released per decay is the same; a short half-life just means the decays happen in quicker succession.
Define medical tracer.
A medical tracer is a radioactive isotope used to track the movement of substances, such as blood, around the body.
Why are gamma emitters usually chosen for medical tracers?
Gamma rays are highly penetrating, so they can pass through the body and be detected outside it, allowing an internal image to be created. They are also less ionising, minimising harm to the patient.
Why are isotopes with short half-lives (of around a few hours) chosen for medical tracers?
This is long enough to carry out the procedure, but not so long that it causes long-term harm.
Define radiotherapy.
The treatment of cancer using radiation.
How does external radiotherapy minimise damage to healthy tissue?
The machine rotates to target the tumour from different angles, minimising the exposure of healthy tissue to the gamma rays.
What happens during internal radiotherapy?
Small pellets of radioactive material are inserted into a tumour, exposing it directly to radiation.
Why is gamma radiation used to sterilise medical equipment?
It is the most penetrating type of radiation, penetrating enough to irradiate all sides of the instruments, and instruments can be sterilised without removing their packaging.
Radiation can kill or damage living cells, cause ______, and cause mutations.
Radiation can kill or damage living cells, cause cancer, and cause mutations.
True or False?
Using radiation in medicine carries no risk.
False.
Radiation can kill or damage living cells, cause cancer, and cause mutations, so its use needs to be kept to a minimum.
Why might it be less risky to use radiotherapy on a cancerous tumour than to leave it untreated?
The risks posed by the radiation are smaller than the risks associated with leaving the condition untreated, for example if the tumour is likely to kill the patient.
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