Physics 2

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  • Created by: kelz0209
  • Created on: 19-04-14 11:25
Name two elements often used as nuclear fuel.
Uranium and plutonium.
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What does nuclear fission produce in addition to energy. Why is this a problem?
It produces a lot of radioactive waste that must be carefully disposed of.
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What are stars formed from?
Clouds of dust and gas.
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Will our sun become a black hole? Explain your answer.
No- our sun is a small star. Only big stars become black holes.
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At the end of its main sequence phrase, what does a small star become?
A red giant.
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Nuclear reactors often use uranium-235. Describe how a chain reaction is set up in a nuclear reactor.
U-235 is bombarded with slow moving neutrons. A U-235 nucleus captures a neutron and splits into two smaller nuclei and releases 2 or 3 neutrons. These neutrons go on to start other fissions, and so on, creating a chain reaction.
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Describe how the heat energy released by nuclear fission is used to generate electricity.
The heat energy is used to heat water to drive a steam turbine and generator.
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The table shows some information about various elements and isotopes. Name the two substances in the table that would be most likely to be used in a fusion reaction.
Deuterium and hydrogen (Fission uses heavy elements, whereas nuclear fusion uses light elements.)
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Explain why scientists are interested in developing fusion power.
Fusion power would allow a lot of electricity to be generated from a plentiful fuel without the large amounts of waste currently produced by fission.
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Explain why fusion is not used to generate electricity at present.
Fusion only works at such high temperatures that it uses more energy than it can produce.
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Stars go through many stages in their lives. Describe how a star is formed.
Stars form from clouds of dust and gas which spiral in due to gravitational attraction. Gravity compresses the matter so much that intense heat develops. When the temperature gets hot enough, nuclear fusion happens and huge amounts of heat and light
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The stable period of a main sequence star can last millions of years. Explain why main sequence stars undergo a stable period.
The forces acting on a main sequence star are balanced, so it doesn't collapse or explode. The heat caused by nuclear fusion provides an outward force to balance the force of gravity pulling everything inwards.
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When main sequence stars begin to run out of hydrogen in their core, they swell and become either a red giant or a super red giant depending on their size. Describe what happens to small stars after their red giant phase.
They become unstable and eject their outer layer of dust and gases as a planetary nebula which leaves a hot, dense solid core known as a white dwarf. White dwarfs then cool to become back dwarfs.
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When main sequence stars begin to run out of hydrogen in their core, they swell and become either a red giant or a super red giant depending on their size. Describe what happens to small stars after their super red giant phase.
They start to glow brightly again and undergo more fusion, and expand and contract several times. Heavier elements are formed and the star eventually explodes in a supernova. The supernova leaves behind a neutron star or a black hole.
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Other cards in this set

Card 2

Front

What does nuclear fission produce in addition to energy. Why is this a problem?

Back

It produces a lot of radioactive waste that must be carefully disposed of.

Card 3

Front

What are stars formed from?

Back

Preview of the front of card 3

Card 4

Front

Will our sun become a black hole? Explain your answer.

Back

Preview of the front of card 4

Card 5

Front

At the end of its main sequence phrase, what does a small star become?

Back

Preview of the front of card 5
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