Physics P2
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- Created by: Izzy
- Created on: 22-05-13 11:21
What did Henri Becquerel discover?
That uranium salts could emit radiation that passes through paper - they were radioactive
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What did Marie Curie discover?
polonium and uranium
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What is special about the nucleus of a radioactive substance? And why is it this?
It's unstable because it's constantly decaying (emitting alpha beta or gamma radiation)
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What are the three main types of radiation? And what properties do they have?
Alpha - can't penetrate paper , Beta - goes through paper, gamma - even more ionising
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Where are the sources for background radiation?
environment (building materials), space (cosmic rays), x ray tubes
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How did ernest rutherford discover the size of the nucleus of an atom? And what were his results?
He Fired alpha particles at a sheet of thin metal foil, used a detector which showed a ray of light every time the particle was deflected. He found that it was very rarely deflected, showing that the nucleus of an atom is extremely small
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What is an isotope?
An element that has the same proton number (atomic number) but a different mass number.
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What happens to the relative formula of an alpha particles when it emits a particle?
Its atomic number decreases by 2 and its mass number decreases by 4
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What happens to the neutrons in a Beta particle?
They change to protons and beta particles
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What happens to the relative formula when a beta particle is emitted?
Atomic number increases by one, mass number stays the same (because the neutron turned into a proton)
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What is the range of alpha, beta and gamma particles?
5cm, 1m, unlimited
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How can you split up A, B and G particles from one beam of radiation?
Use an electric field, A particles go to the negative side, B particles go to the positive side, Gamma particles aren't attracted
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Why are alpha particles more harmful in the body than beta or gamma?
Because they are more ionising in the body - damage tissue and cells
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What is half life of a radioactive isotope?
The average time it takes for the number of nuclei in the isotope to halve
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What is the activity of a radioactive source?
Number of nuclei that decay per second
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What does the use of radioactive isotopes depend on?
its half life, and the type of radiation it gives out
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What is carbon dating?
A process used to find the age of ancient wood by counting
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What is uranium dating?
Process used to find the age of igneous rocks, which contain uranium
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What is nuclear fission?
The splitting of a nucleus into two equal fragments, followed by the release of 2 or 3 neutrons
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What causes nuclear fission?
When the neutron hits a uranium-235 or plutonium-239 atom and splits
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What does nuclear fission cause in a nuclear reactor?
A chain reaction
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Why is a nuclear reactor built with strong thick walls?
To withstand high temperatures, and to absorb radiation
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What do control rods do in a nuclear reactor?
They control the amount of neutrons by absorbing them so that only one is released to cause more fission
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What is nuclear fusion?
The process of forcing two nuclei close enough together AT A HIGH SPEED so they form a single larger nucleus
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Why does the sun release energy?
Because fusion releases energy and there is fusion in the sun's core
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What is the definition of the galaxy?
Collection of billions of stars held together by their own gravity
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What was the universe made of before galaxies and stars were formed?
Cloud of hydrogen and helium
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The force of gravity pulled all other matter into the galaxy. true or false?
True
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Describe the life cycle of a star about the same size as the sun
Protostar (gets hotter and denser), --> main sequence star (Forces in it are balanced) -->Swells and becomes hotter to be a red giant --> Collapses and heats up (white dwarf) --> cools fades (black dwarf)
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Describe the life cycle of a star much bigger than the sun
Protostar (gets hotter and denser), --> main sequence star (forces in it are balanced) --> swells and heats up (red supergiant) -->core compresses and explodes (supernova)
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If the mass is high enough, what happens after the supernova?
Core becomes a neutron star, if very big becomes a black hole (such a strong magnetic field that nothing can overcome it)
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What elements are formed in a light star?
helium and carbon (from fusion)
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What elements are formed in supernovas?
Iron and heavier elements
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What is the sun and solar system formed by?
The debris of a supernova
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Other cards in this set
Card 2
Front
What did Marie Curie discover?
Back
polonium and uranium
Card 3
Front
What is special about the nucleus of a radioactive substance? And why is it this?
Back
Card 4
Front
What are the three main types of radiation? And what properties do they have?
Back
Card 5
Front
Where are the sources for background radiation?
Back
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