uses of radioisotopes Flashcards
what is background radiation due to?
radioactive substances present in rocks and soil (especially granite)
cosmic rays from space
man-made sources including radioactive waste from industry and hospitals
what is background radiation?
ionising radiation that is always present in the environment
where does background radiation mainly come from?
rocks especially granite and cosmic rays
what are radioisotopes used for?
as tracers in industry, research and medicine
what are tracers used for?
detect leaks or blockages in underground pipes
find the route of underground pipes
track dispersal of waste
monitor the uptake of fertilisers in plants
check for a blockage in a patients blood vessel
what radiation is used in smoke detectors?
alpha
how is a tracer used to detect a leakage in a pipe?
a small amount of a suitable radioisotope is put into the pipe
a detector is passed along the ground above the path of the pipe to track the progress of the radioisotope
an increase in activity is detected in the region of the leak or blockage and little or no activity is detected after this point
what do many smoke detecters contain?
a radioisotope such as amercium-241 that emits alpha particles
what happens in a smoke detector when there isnt smoke?
the alpha particles hit air particles and ionise them.
the posotive ions and negative electrons move towards the negative and posotive plates.
this creates a tiny current that is detected by electronic circuitry in the smoke alarm
what happens in a smoke detector when there is smoke?
some alpha particles hit the smoke particles so there is less ionisation of air particles
the smoke detector senses the drop in current and sets off an alarm
what are some examples of background radiation made by human activity?
waste products from hospitals
waste products form nuclear power stations
what radioactive substance do most rocks contain?
uranium
after a uranium isotope has decayed what does it form?`
a stable isotope of lead
how can a rocks age be found?
by comparing the amounts of uranium and lead present in a rock sample
what does uranium-238 do?
decay
