Unit 2 OCR GCSE Physics

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

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

• 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.

• 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.

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

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

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.

• 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. 

• 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. 

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. 

• 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. 

(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) 

Electrons - Energy - Flows around ciruit.

Made of silicon (photocells)

SILICON ATOMS absorb energy.

Some electrons come loose- Renewable energy 

No Sunlight, No Power

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.