uses of radioactivity

uses of radioactivity

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The Uses of Radioactivity
Smoke detectors:
Alpha radiation is used in a smoke detector. The alpha radiation ionises the air inside
the detector producing lots of carbon particles. The charged particles move across
the gap and the current produced is picked up by a detector a few cms away. If
smoke enters the detector it absorbs the alpha radiation, resists the current. This
sets off the alarm.
Measuring thickness
The absorption of radiation can be used to monitor and control the
thickness of different materials. A radioisotope is chosen that emits
radiation that will pass through the material but some radiation will be
absorbed
If the thickness of the material remains constant the count on the GM tube
remains constant If the material gets thinner, more radiation passes
through and the count rate increases. Changes in the count rate are used to
control the p................. on the rollers.
To monitor the thickness of paper beta radiation is used
To control the thickness of metal sheeting gamma radiation is used
Sterilisation of food and medical instruments:
Very high doses of ionising radiation can kill cells and single celled organisms. They are
used to:
Kill bacteria in food to allow it to keep longer. This could prevent food from
going bad on a long journey
Sterilise medical instruments to prevent infection. This kills bacteria without
the need for high temperatures
Medical uses ­ diagnosis and treatment
Diagnosis
Sometimes a source of radiation may be used inside the body in order to find out
what is wrong. A substance is put into the body that contains a radioactive element
called a radioactive tracer The isotope must be a radiation emitter as this is the only
type of radiation that is not absorbed by the body. A tracer is a radioactive substance
that allows us to follow a variety of pathways. They behave like transmitters inside
the body. The radiation emitted escapes from the pathway and can be detected
outside the body by a gamma camera. This allows us to map out the pathway.
Examples:
Radioactive iodine (a gamma emitter) is used to see if the thyroid gland is
working properly. A dose of iodine is given to the patient and the thyroid
gland takes up the iodine. Doctors can then detect the radioactivity of the
patient's throat. All medical tracers are pure gamma emitters as only gamma
radiation can escape from the patient. It is important that the half life of the
radioisotope is suitable for the procedure (iodine has a half life of several
days).
Research the uses of technetium in medical imaging
Treatment - Radiotherapy
Very high doses of ionising radiation can kill cells. They are used to:

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Kill cancer cells in radiotherapy treatment. The size and shape of the tumour
are mapped out very carefully and then a beam of radiation is directed at the
tumour to kill the cancerous
Radiocarbon Dating
The carbon atom is used for researching into the radiocarbon dating. The age of
archaeological specimens can be calculated by looking at the amount of
carbon-14 in a sample. The method is called carbon dating or radio dating.…read more

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