1. L.O – Assess understanding of P2 Identify areas to focus revision on. Know some strategies to improve understanding in these areas. Revision of the P2 Living for the Future

2. P2a – Collecting Energy from the Sun • The Sun transfers energy to Earth as light and heat. • Photocells transfer the Sun’s light into electricity, they can operate in remote locations and have a power that depends on the surface area exposed to sunlight. • D.C means Direct Current and is current in the same direction all the time. E.g. from a battery or from a photocell. • The power output from a photocell depends on the intensity of the light and the size of the surface area that can absorb the light. • Advantages of Photocells are: easy to maintain, no cables, use renewable energy source, no pollution and they last a long time. • Disadvantages of Photocells: they cannot work in the dark, so not at night or if the weather is bad. You need a large panel for a reasonable amount of electricity.

3. Disadvantages of Photocells: they cannot work in the dark, so not at night or if the weather is bad. You need a large panel for a reasonable amount of electricity. • The Sun’s energy can be harnessed in other ways, such as in solar heating and solar cooking. • Wind turbines are used to convert kinetic energy from the wind into electricity. • Advantages of wind turbines: use renewable energy so will not run out, no pollution. • Disadvantages: It needs to be windy, they are large, they are noisy and some people think they spoil the countryside.

4. P2b – Power Station 1 • If you move a wire near a magnet you generate electricity in that wire – this is called the dynamo effect. • The current produced is AC, Alternating Current, as the magnet spins and therefore faces different ways, making the current keep changing direction. • You can increase the electricity produced in a number of ways: • Increase the number of coils • Wrap the coil around an iron core • Move the magnet (or the coil) faster • Use a stronger magnet. • the energy transfers which take place in a conventional power station

5. The frequency of an ac current is the number of cycles of output per second. • Energy transfers which take place in a conventional power station: Chemical  Heat  Kinetic  Electrical • Some energy is wasted in a power station, as heat energy. Efficiency = energy output / energy input. (so the less energy wasted the better its efficiency) • Transformers can be used to increase or decrease voltage.

6. Transformers are used in the national grid. • A step up Transformer is used to increase the voltage before it enters the overhead power cables (this keeps the current small and therefore reduces energy loss) • Then a step down transformer take the voltage back down to a useable size before it enters our houses. (230v)

7. P2c – Power Station 2 • The common fuels used in power stations are coil, oil and gas, or biomass. Nuclear power is also becoming more popular. • A worry about Nuclear power is that the waste from is radioactive and therefore hard to dispose of. • Advantages: Lots of uranium available, no pollution. • Disadvantages: Uranium will eventually run out, it is expensive to shut down power stations, they are expensive to run, there is a risk of accidents. • Ionising radiations can cause cancer. • Plutonium is a waste product from nuclear reactors that can be used to make nuclear bombs. • Burning fuels releases energy, uranium rods release energy and biomass can be fermented to generate methane, which can then be burnt.

8. Different appliances use different quantities of power and that this is measured in watts or kilowatts. • To calculate the power rating of an appliance you use • Power = current x voltage [P=IV] • To calculate the number of kilowatt hours, use power in kilowatts and the time in hours. • To calculate the cost of energy: • Cost = power x time x cost per unit