Uses of radiation Flashcards
uses of gamma rays (4)
kill cancer cells
sterilise surgical instruments
diagnose cancer
preserve food
How is gamma used to kill cancer cells?
beams of gamma rays can be directed at cancer cells to kill them
How is gamma used to sterilise surgical instruments?
gamma rays can be used to sterilise plastic instruments that can’t be sterilised by heating
How is gamma used to diagnose cancer?
a tracer solution containing a radioactive isotope that emits gamma rays is injected into the body and taken up by cells which are growing abnormally. The places in the body where the tracer collects are detected with a gamma camera.
How is gamma used to preserve food?
food irradiated with gamma rays will last longer as microbes are killed by the high energy gamma rays. The food does not become radioactive.
How do smoke alarms work?
-contain a source of alpha particles (e.g. americium-241)
the source gives off a constant stream of alpha particles
alpha particles ionise the air and these charged particles move across the gap forming a current
smoke enters the smoke detector
smoke in the machine will absorb alpha particles and make the current fall
a detector senses the amount of current
siren will sound when the current falls
How is radiation used to control thickness of paper?
beta radiation is used
a source of radiation is aimed at the paper
a detector senses how many particles get through
if the paper is too thick, not as many get through and the roller press together harder to make the paper thinner, or move apart to make it thicker
Explain why beta particles are used to control the thickness of paper. [3]
alpha particles would not go through the paper at all
gamma rays would pass through the paper too easily, and the amount getting through would hardly change with small changes in the thickness of the paper
State three uses of ionising radiation [3]
sterilising surgical equipment killing cancer cells preserving fruit smoke alarms thickness testing x-ray photographs
Explain why the radiation in smoke alarms is not dangerous to people in homes [3]
it contains alpha particles, which have a short range in air and cannot reach the body
Suggest how ionising radiation can be used to find cracks in underground pipes [3]
water is injected with a gamma source
when water reaches a crack, water will pass out of the pipe into the surrounding ground, so a higher reading of gamma-rays is detected at the surface above the crack in the pipe
