Being energy wise

Test your knowledge of energy use at school and at home

Learning Objectives

• To know that many everyday appliances use electricity.

• To know that electrical appliances have power ratings measured in watts or kilowatts.

• To know the difference between ‘power’ and ‘energy’.

• To know that, if you want to work out how much energy an appliance has used, you need to know its power rating and how long it is used.

Work with a partner or in a small group….

Can you list all the electrical appliances you use in your classroom?

How many did you have? Did you think of ….

• Lights

• Heating

• Computer

• Television

• Radio

• Video or DVD

• Tape recorder

• Battery powered toys

• Fans

• Clocks

• Digital camera

• Digital camcorder

• Digital voice recorder

• Telephone

What other appliances did you have?

TRUE or FALSE?• Appliances on standby don’t use energy.

• FALSE

• Some types of light bulbs use a lot less energy than others.

• TRUE

• Lights need to be on all the time.

• FALSE

• We can all help to use less energy.

• TRUE

So, what appliances do you think use the most energy?

• Discuss with a partner

What appliances need lots of power to make them work?

What appliances are used for long periods of time?

Do all appliances need the same amount of energy to work?

How do we measure electricity use?

• Power – we measure the rate at which an appliance takes power from the electricity supply in watts or kilowatts (W or kW).

• 1 kilowatt is the same as 1000 watts.

• Look at the labels on some appliances – which use the most power?

How long is it on for?

• Energy – we work out how much electrical energy is used by multiplying the power of the appliance (kW) by the number of hours it is used for. This gives the amount of energy used in kilowatt-hours or kWh.

• One kWh is the energy used when one kilowatt of power is used for one hour.

Which uses the most energy?

• A 1 kW microwave oven, used for 2 hours?

• A 1 kW vacuum cleaner, used for 1 hour?

• A 3 kW kettle, used for 1 hour?

Microwave oven 1 kW x 2 hours = 2 kWh

Vacuum cleaner 1 kW x 1 hour = 1 kWh

Kettle 3 kW x 1 hour = 3 kWh

It’s the kettle – were you right?

Remember that 1000 watts = 1 kilowatt

If one light bulb uses 20 watts of power…..How many light bulbs would use 100 watts?How many light bulbs would use 1000 watts or 1kW?

If all these light bulbs were left on all day from 8 in the morning to 6 at night, how many kWh of electricity do they use?

How many light bulbs are in your school?

Power and energy

How does this help us to be energy wise?

• What have you learnt from this?

• How could you use this information in a lighting survey?

Where does electricity for lighting come from?

Watch some of the international films to see how electricity can be generated in different ways

• Where does the electricity come from?• How do the families pay for their lighting? • What environmental costs are there?

• Where does the electricity come from for the lights in your home and at school?

• How does your family pay for lighting?• What environmental costs are there?

How can we monitor how much energy we use?

Watch the UK school films to see how pupils are monitoring and reducing their energy use.

Are these pupils doing things that you do too?Are they doing things you would like to do?Discuss with your teacher the good ideas that you find.