Half-Life&Uses of Radiation Flashcards
What is a well-known example of a radiatioative isotope used in modern medicine? What does it do?
Iodine-131
It is absorbed by the thyroid gland and gives out radiation which can be detected to indicate whether the thyroid gland is taking in iodine as it should
All isotopes which are taken into the body must be what?
Gamma or Beta
How are gamma rays used to keep food fresh for longer?
if food is exposed to a high dose of gamma rays, the gamma rays will kill all microbes keeping the food fresh for longer
What is the advantage of irradiation as opposed to boiling (to sterilise) ?
Irradiation doesn’t involve high temperatures so things like fresh apples can be sterilised without damage
What type of isotope needs to be used for the sterilisation of food and surgical instruments?
A very strong emitter of gamma rays with a reasonably long half-life so that it doesn’t need replacing too often
How do you smoke detectors work?
A week alpha source is used to ionise the air between two electrodes so that the current can flow. If the alpha radiation is absorbed by smoke the current stops and the alarm sounds.
Why is nuclear radiation dangerous
Because it is ionising and can damage cells
Which type of radiation is most dangerous inside the body alpha particles or beta particles?
Alpha particles
Suggest two reasons why alpha sources aren’t used as medical traces
Alpha radiation is stopped by the bodies tissues and so wouldn’t be detected externally
It is strongly ionising which makes it dangerous inside the body
Suggest one reason why it is important that radioactive sources used in the hospital sterilising machines have a long half life
So that the device lasts a long time and therefore doesn’t need to be replaced as often
What is the deffiniton of half life?
Half life is the average time it takes for the number of nuclei in a radioactive isotope sample to halve
