P1a Energy and Energy Resources

1 Heat TransferConductionConvectionRadiation

2 Using energyForms of energy

ConservationEfficiency

3 Electrical energyDevicesPower

National Grid

4 Generating ElectricityFuels for electricityRenewable sources

Environment

Use the hyperlinks to jump to each

topic.

Yellow boxes give key points

1.1 Thermal Radiation1. Heat transfer by electromagnetic waves.2. All objects emit (give out) thermal radiation.3. Hotter objects emit more thermal radiation.

1.2 Surfaces and radiation1. Emitting heat (giving out);– Dark matt best,– Shiny surfaces worst.

2. Absorbing heat (taking in);– Dark matt best,– Shiny surfaces worst.

1.3 Conduction – Heat travels through the material

1. Metals conduct heat very well - ‘free’ electrons inside.2. Non-metals are poor conductors – no ‘free’ electrons. 3. Good insulators trap air inside e.g. Fibreglass.

1.4 Convection – Hot fluids rise1. Only takes place in liquids and gases (fluids).2. Heating a liquid or gas makes it less dense.3. Less dense fluids float on more dense fluids.

1.5 Heat transfer by design1. Radiators have a large surface area to

lose heat easily.2. Small objects lose heat faster than

large objects.3. Heat loss from a building can be

reduced by using:– Aluminium foil behind radiators,– Cavity wall insulation– Double glazing– Loft insulation

2.1 Forms of energy1. Energy exists in different forms;

– Nuclear, Chemical, Strain, Gravitational, Electrical, Light, Sound, Kinetic and Heat.

2. Energy can change (transform) from one form into others.

2.2 Conservation of energy1. Energy cannot be created or destroyed.2. Energy can be transformed from one form into another

but the total amount of energy always remains the same.

2.3 Useful Energy1. Energy in the form and place which we want it.2. Energy that is not useful is wasted.3. Useful and wasted energy both end up warming

up the surrounding area.4. The more spread out energy becomes the harder

it is to use it.

2.4 Efficiency1. Energy is measured in Joules.2. Efficiency = useful energy transferred

Total energy supplied3. Wasted energy reduces efficiency.

3.1 Electrical devices1. Electric current transfers electrical energy.2. Electrical energy can be used for;– Heating, lighting, movement (electric motors), sound and

visual images.

3.2 Electrical power1. Power is measured in watts (W), equal to 1 Joule per second.2. 1 kilowatt (kW) = 1 000 watts. (Mega = 1 000 000)3. Power (Watts) = Energy transferred (in Joules)

time taken (seconds)

3.3 Using Electrical Power1. Energy (kilowatt-hours, kWh) = power (kW) x time (hours)2. Total cost = number of kWh x cost per kWh

3.4 The National Grid – a network of cables and transformers

1. Step up transformers increase power station voltages to the grid.2. Step down transformers decrease grid voltages to our homes.3. High grid voltages reduce energy losses increasing efficiency.

4.1 Fuel for electricity

1. Electricity generators in power stations are driven by turbines.

2. Much more energy is released by uranium per kilogram than fossil fuels.

4.2 Wind and Water1. Wind turbines uses kinetic energy from the wind to generate electricity. (Sun)2. Wave generators convert the kinetic energy of waves into electricity. (Sun)3. Hydroelectric generators convert the gravitational energy of water flowing

downhill into electricity. (Sun)4. Tidal power stations convert gravitational energy of trapped high tides into

electricity. (Moon)

4.3 Sun and Earth

1. Solar energy can be used by;– Solar cells make electricity,– Solar panels heat water.

2. Geothermal energy comes from the energy released by radioactive substances deep inside the Earth.

4.4 Environment

1. Fossil fuels produce greenhouse gases (CO2).

2. Nuclear fuels produce radioactive waste.3. Renewable energy resources can affect plant

and animal life.