Where do radioactive substances give out radiation from?
The nuclei, no matter what is done to them.
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What types of radiation is given out by radioactive substances?
Alpha, beta and gamma.
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Where does background radiation come from?
Radioactivity of naturally occuring unstable isotopes which are all around us - in the air, in food, in building materials and in the rocks under our feet.
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What people are more at risk of cancer due to radiation exposure?
Miners, radiographers in hospitals, jet pilots and nuclear industry workers. This is all because they work in areas of high radiation.
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How many neutrons and protons do alpha particles have? What nuclei is this similar to?
2 protons and 2 neutrons, the same as helium nuclei.
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What are alpha particles like?
They are big, heavy and slow moving. They can be stopped quickly even in air. They are also strongly ionising, which means they bash into a lot of atoms and knock electrons off, creating lots of ionising.
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What are beta particles?
Beta particles are electrons. They are in between alpha and gamma in terms of their properties.
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What are beta particles like?
They move quite fast and are quite small. They penetrate moderately into materials before colliding, have a long range in air and are moderately ionising too.
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What happens every time a beta particle is admitted?
A neutron turns to a proton in the nucleus.
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What are gamma rays?
Very short wavelength EM waves. They are the opposite to alpha particles. They penetrate far into materials without being stopped and pass through air. They are weakly ionising because they pass through and dont collide with atoms.
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Do gamma rays have mass and charge?
No.
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What charge do alpha and beta particles have?
Alpha have a positive charge and beta have a negative charge.
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Do alpha and beta get deflected in magnetic or electric field?
Yes.
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What is half-life?
It is the average time it takes for the number of nuclei in a radioactive isotope sample to halve.
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What is the problem trying to measure half life?
The activity never reaches 0.
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How is radiation used in smoke detectors?
Smoke detectors - A weak source of alpha radiation is placed in the detector, close to 2 electrodes. The source causes ionisation and a current flows between the electrodes. If there is a fire then smoke will absorb the radiation and the current stop
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How does radioactivity work?
Gamma rays kill all living cells, so can be used to kill cancer cells. The gamma rays have to be directed carefully and at just the right dosage so only the cancer cells are killed.
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What is the order of the starrs?
Protostar -- Main Sequence Star -- Red Super Giant or Red Giant -- Supernova or white dwarf -- neutron star -- black hole
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What is current?
It is the flow of electric charge round the circuit. Current will only flow through a component if there is a potential difference across that component.
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What is potential difference?
It is the driving force that pushes the current around.
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What is resistance?
It is anything in the circuit which slows the flow down.
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What is static electricity?
It is about charges which aren't free to move. This causes them to build up in one place and it often ends with a spark or a shock.
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Other cards in this set
Card 2
Front
What types of radiation is given out by radioactive substances?
Back
Alpha, beta and gamma.
Card 3
Front
Where does background radiation come from?
Back
Card 4
Front
What people are more at risk of cancer due to radiation exposure?
Back
Card 5
Front
How many neutrons and protons do alpha particles have? What nuclei is this similar to?
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