Unit 2 OCR GCSE Physics

A set of revision cards on P2 GCSE Physics. 

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Photocells

  • Generate electricity from light.
  • Generate direct current. (DC)
  • Mains electricity- keeps switching direction.
  • Flows same way around circuit the whole time. (DC)
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Coppernicans Model

  • 1543
  • Sun is at the center.
  • All planets orbit the sun.
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Nuclear Power

  • Doesn't produce CO2
  • Steam works the generator.
  • Fuel leaks- waste- expense
  • Difficult and dangerous to dispose.
  • Makes lots of energy- more energy than chemical reactions.
  • Long time to start up.
  • Cheap.
  • Uranium- atoms split into two- releases heat energy.
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Gamma

  • No mass, no charge
  • Stopped by lead or thick concreate.
  • Penetrate a long way.
  • EM Radiation- Kills all living cells- treats cancers
  • Can sterilise medical equitment.
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Alpha

  • Stopped quickly with paper.
  • Big and heavy.
  • 2 protons, 2 neutrons.
  • Used in smoke detectors- weak source of radiation- smoke absorbs radiation. 
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Beta

  • Stopped by a sheet of Aluminium.
  • Move fast.
  • Electrons- thickness control.
  • Small tracers- injected into patients.
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Greenhouse Effect Part 1

Gas lets in heat and light. Absorbed by things in the room, heating them up.

Light from sun- short wavelength- so it can pass through glass into a room.

Heated things in room emit radiation of a longer wavelength- can't escape. (infared) Just get reflected back instead.

Keeps heat inside of buildings.



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Greenhouse Effect Part 2

  • Atmostphere traps HEAT- various gases- filter out some radiation- absorob/ reflect radiation of certain wavelength. (infared)
  • Visible light and radio waves pass through the atmostphere. 
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Greenhouse Effect Part 3

  • Earth absorbs SHORT WAVELENGTHS. (EM Radiation) - warms the surface of the Earth up.
  • Earth then emits some EM Radiation back into SPACE.
  • In turn we cool down.

Earth emmits LONGER LENGTHS of Radiation. (infared) (heat)

Absorbed by CO2, CH4 and Water Vapour. 

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Greenhouse Effect Part 4

RE- RADIATE heat in different directions back to Earth.

Insulating layer stops the Earth loosing heat at night- Atmostphere.

Humans increase the amount of greenouse gases. 

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Dynamo Effect

  • Electromagnetic induction: The creation of a voltage in a wire which is experiencing a change in a magnetic field.
  • Electromagnetic induction to transform kinetic energy (moving things) into electrical energy- powerstation turbine.
  • EM= Electromagnetic 

1) Electrical conductor - Coil of wire usually moves around a magnetic field.

2) Magnetic Field through a electrical conductor changes. 

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Dynamo Effect Part 2

(Gets bigger, smaller or reverses)

If the direction is reversed then so is the voltage/ current.

Want a BIGGER VOLTAGE/ CURRENT then INCREASE:

1) Strength of the MAGNET.

2) The amount of turns on the COIL.

3) The SPEED. (of movement) 

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Electrons

Electrons - Energy - Flows around ciruit.

Made of silicon (photocells)

SILICON ATOMS absorb energy.

Some electrons come loose- Renewable energy 

No Sunlight, No Power



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Solar Energy

HEAT and LIGHT! 

Some is stored as fossil fuels. 

Sun heats the air- hot air rises, cold air comes in to take it's place.

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