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6 June, 2014. Electrical Devices. Keywords: Electrical, kinetic, sound, light, heat, power, joule, watt, kilojoules, kilowatt, transfer, transformation. Outcomes. All students should be able to:
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6 June, 2014 Electrical Devices Keywords: Electrical, kinetic, sound, light, heat, power, joule, watt, kilojoules, kilowatt, transfer, transformation
Outcomes All students should be able to: • Give examples of devices that use electricity and describe the useful and wasted energy transformations. Most students should be able to: • Describe what power is and give the units of Energy and Power. • Explain the advantages and disadvantages of using electrical appliances in different situations. Some students should be able to: • Use the definition of power to calculate the amount of energy an appliance uses and give the correct units.
ALL Starter: My Appliances • Write down all the electrical appliances you have used today in a table like below: • Use these keywords to help you: light, sound, heat, kinetic, electrical,
Why is electricity an important energy resource in the home? What different electrical appliances do you have at home? Mixer Fan heater Toaster Espresso machine Bread maker Kettle Dishwasher Freezer Fridge Microwave Oven Extractor fan Food processor
Why is electricity an important energy resource in the home? Consider my kitchen appliances again: Freezer Fridge Microwave Oven Extractor fan Food processor Mixer Fan heater Bread maker Dishwasher Have a motor Have a heater Fan heater Toaster Espresso machine Bread maker Kettle Dishwasher Oven
MOST Why is electricity an important energy resource in the home? most domestic appliances use electricity What tasks can electricity be used for? Heating, Moving, Cooling, Lighting, Entertainment Task: In pairs: Discuss, then write down your answers1 For each of the 5 tasks, come up with as many ways of doing this task without using electricity. 2 Now come up with advantages and disadvantages of these other methods compared to using electricity.
Electricity vs Other Resources What are the 4 advantages? • no pollution at point of use • easy to use • can be used to operate a large variety of domestic appliances • no storage problems What are the 3 disadvantages? • cannot be stored so risk of power cut • risk of shock • needs cables to the house- problem for remote properties If you didn’t get these: jot them down now!
E P T Power • What is power? • Power is the rate at which energy is transferred. • Power in Watts is the amount of Joules transferred in 1 second.
SOME Yay… Electrical Appliances Demo Time!! • Your teacher will show you a number of devices and measure their power outputs. • Make a table to show the energy that each device has. You must label each column and use units correctly. Include a column for time and energy. • Now draw a graph. What type of graph will you draw? Explain why you have chosen the graph you have. (Hint: it depends on the type variables – continuous or categoric.) • If all the appliances were running for 60 seconds, how much energy would they use?
Plenary: Big Q – Does electricity run like clockwork? • A clockwork radio uses a spring to turn a generator inside the radio to make it work. 30 seconds of winding is enough to provide 60 minutes of radio play time. It has a power rating of 10 Watts. • ALL: Describe the input energy, the useful energy and the wasted energy. • MOST: What is the advantage of a clockwork radio over a battery powered one? Where might it be used? What is meant by “It has a power rating of 10 Watts.” • SOME: How much energy, in Joules, would it take to have the radio on for 24 hours and how long would you have to wind it for?
