P3 Revision summary

Primary sources of energy. Fossil fuels. Nuclear fuel. Renewable energy sources. What does primary mean?

Renewable energy. How many renewable energy sources can you name? Solar energy. Geothermal. Tidal. Wind. Wave. Hydroelectric. Energy from biomass.

Electricity Is electricity a primary or secondary energy source? And why? Secondary-because it is generated in power stations from fuels or other energy sources.

Electrical appliances. Electricity is convenient because it is easily transmitted over distances and can be used in many ways.

How does a power station work?

How many did you get? 1. Furnace and boiler. Heats water to produce steam 2. Turbine. Steam drives the turbine which is coupled to the generator. 3. Generator. Produces the electricity. 4. Transformer.

Generator Generators produce a voltage across a coil of wire by spinning a magnet near it.

The graph shows that the demand for energy is increasing. But why?

Increasing energy demand. Growing world population Improving standard of living

What is nuclear fuel? A nuclear fuel is one where the energy is released from changes in the nucleus. A common nuclear fuel is uranium. Refined uranium. Uranium containing ore.

Nuclear Power Station. The only difference between a nuclear power station and a conventional power station is how the water is heated. Why is there a concrete shield around the reactor core?

A downside to nuclear energy. Nuclear power stations produce radioactive waste. What do you understand by the term radioactive?

Radioactive. When a substance emits (gives out) ionising radiation all the time it is called radioactive. Ionising radiation can damage living cells.

Ionising and non-ionising. Sort the different types of radiation into ionising and non-ionising. Why is ionising radiation more dangerous than non-ionising?

Why is ionising radiation dangerous? Ionising radiation can damage living cells. This can lead to cancer.

Irradiated food. What do you notice about the strawberries that This is the sign for irradiated food. What do you notice about the strawberries that have been irradiated?

Irradiation and contamination. Contamination – when the radioactive source enters the body or gets on skin or clothes Irradiation – exposure to a radioactive source outside the body. Which is more dangerous, irradiation or contamination and can you explain why? (Use the definitions above to help you).

Power When an electric current is passed through a device electric current is transferred from the supply to the device. The rate at which this energy is transferred is called POWER. Power is measured in WATTS (W).

Calculating the energy transferred To calculate the energy transferred use the following equation; Energy transferred (J) = Power (W) x time (s) Question – An electric kettle connected to the 230 V mains supply draws a current of 10 A. Calculate A) The power of the kettle. B) The energy transferred in 1 minute

Joules and Kilojoules There are a 1000 J in 1 kJ. Convert the following joules into kJ 3000 J 25000 J 500 J

The Kilowatt Hour The energy transferred when a power of 1kilowatt (1000W) is used for 1hour.

The kilowatt hour (kWh) = 1000W x (60 x 60s) = 3 600 000J Why do energy companies use kWh instead of joules to measure your electricity?

Kilowatt-hour The kilowatt-hour is a unit of energy and is calculated by: Energy transferred = power x time (in kW h) (in kW) (in hours)

Example A kettle has a power rating of 1000W it is used for 3 hours a day. How much energy is transferred in one day?

How much does your electricity cost? N power supplies electricity in kilowatt-hours called a unit. Each unit costs 7p. A typical family uses 10kWhr a day: How much does it cost them a day? 10KWhrs = 10 units 10 units x 7p = 70p It costs the family 70p a day for their electricity

Energy cost OR Power (KW) x time (hours) x cost per unit Energy used (KWhr) x cost per unit = total energy cost OR Power (KW) x time (hours) x cost per unit

Sankey Diagram Sankey diagrams show where the energy goes.

Interpreting a Sankey Diagram. What do the different direction of the arrows tell you about the energy efficiency?

Sankey Diagram The thickness of each arrow is drawn to scale to show the amount of energy

Conservation of energy What do you notice about the total amount of energy before and the total amount of energy after? Explain what conservation of energy means?

Efficiency Although the total energy out is the same, not all of it is useful.

Efficiency Efficiency is how well it transfers the energy you put in to useful energy. The efficiency of ‘something’ can be worked out by: Useful energy output x 100% Total energy input

Starter: What factors need to be considered when choosing an energy source?

Choosing and energy source. What factors need to be considered when choosing an energy source? A) Environmental impact. B) Economics. C) Waste produced. D) Carbon dioxide emissions.