What are the two types of charging and what are they?
Negative electrons moved by friction. Negative is gain of electrons, positive is loss of electrons.
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What are the forces?
Opposite charges attract, like charges repel.
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What does a defibrillator do?
Good contact with skin on chest. Static charge makes heart contract once.
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How does paint spraying work in terms of charge?
Particles of paint are charged as they leave the paint gun. The particles spread out as they repel each other. If the car is negatively charged then the paint would be more attracted to it.
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How does a smoke precipitator?
Particles of smoke are charged as they pass through a metal grid. Smoke attracted to oppositely charged plates in the chimney.
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What are dangers of static electricity?
Petrol station - friction builds static, spark, explosion.
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3 things about the live wire?
Brown, bottom right, carries current.
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3 things about neutral wire?
Blue, bottom left, completes current.
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What is the earth wire?
Yellow and green, top. Carries charge to the earth to prevent electric shocks.
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What is a fuse?
Thin metal wire melts if too much current flows, circuit breaks.
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What is meant if a plug is double insulated?
Made of plastic (insulator), don't need an earth wire.
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What is a current?
Flow of electrons
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What is resistance?
Caused by collisions between electrons and ions. Thinner, longer wires have most resistance.
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What are the properties of an ultrasound?
Too high for humans to hear, over 20000Hz.
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What type of wave is an ultrasound?
Longitudinal - wave and particles move in parallel.
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What is alpha radiation?
a^4 2 , Blocked by paper, highly ionising, damages cells.
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What is beta radiation?
B^0 -1 , blocked by aluminium
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What is gamma radiation?
y^0 0 , reduced by lead, least ionising.
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What is a half life?
Time for amount of radiation to halve.
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What radiation do medical tracers use?
Gamma - can escape. Short half life.
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What radiation is used to kill cancer?
Gamma - rotate source to limit damage to healthy cells.
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What is a fission reaction?
Uranium split by 1 neutron into 2 smaller nuclei and 3 more neutrons. This becomes a chain reaction.
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