Unit 2 - Nuclear Decay/Radiation Flashcards
What is a beta particle?
An electron (released from the centre of an atom)
What is an alpha particle made of?
2 protons and 2 neutrons.
How far can an alpha particle travel?
Just a few cm in air and is stopped by paper.
Name the most ionising type of nuclear radiation.
Alpha - safe outside the body as it can’t get through skin, but very dangerous inside the body as it is so ionising.
Why is a radioactive sample with a short half life used in the body as a medical tracer?
It doesn’t last long in the body or There’s less of a risk of ionisation of cells as radioactivity levels decrease quickly.
What affects the half life of a radioactive sample?
Nothing, decay is a random process that can not be changed.
Define half life.
The time taken for the original count rate/number of radioactive atoms of a radioactive sample to decrease by half.
If a sample of radioactive atoms have a half life of 2 days how long would it take for the count rate to go from 2000 counts per second to 125 counts per second?
2000 - 1000 - 500 - 250 - 125 = 4 half lives = 8 days overall.
Why is a source of gamma radiation used as a medical tracer?
Gamma penetrates the skin and tissue so can be detected outside the body. It is also the least ionising.
Give a profession which would experience a higher level of background radiation than an average person.
Pilot (more cosmic rays)Frequent flyer/air hostess/Stewart (ditto)Worker in a nuclear power station
Give a natural source of background radiation.
Radon gasCosmic raysFood and drinkBuildingsRocks
Give an artificial source of background radiation.
Nuclear weapons testingNuclear power station leakMedical x rays, gamma rays produced in radiotherapy.
Which of these questions can not be answered by science?Where does background radiation come from?What is meant by the half life of a radioactive source?Should radioactive waste be dumped into the ocean?
Should radioactive waste be dumped into the ocean?This is a question in which the answer is opinion based. Experiments can not be done to answer this question.Watch out for ‘should’ questions! They want your opinion.
Which type of nuclear radiation is the least ionising?
Gamma. All nuclear radiation ionise cells but gamma is the most weakly ionising.
