KEY WORDS RENEWABLE ENERGY CONSERVED DISSIPATED USEFUL WASTED EFFICIENCY SANKEY

Forms of Energy Learning Objectives: Wednesday, 19 September 2018 Forms of Energy Learning Objectives: Recognise the different forms of energy How can we describe energy transfer Realise that energy cannot be created or destroyed 2

Energy Transfers Write down the energy transfers that happen in each appliance and label the useful and wasted energies. Toaster Crane Kettle Rocket Car engine Firework Speaker TV

Energy cannot be created or destroyed

Useful Energy and Efficiency You will be able to: Recognise the different forms of useful energy. Realise where the wasted energy goes to. Draw an accurate Sankey diagram. Calculate the efficiency of a device.

You have to draw each shape below as accurately as possible..... Let the games begin You have to draw each shape below as accurately as possible.....

Now swap books and harshly mark your partner’s work

These show the energy transfers in a device Sankey Diagrams These show the energy transfers in a device Useful energy out Energy in Wasted energy out

Sankey Diagrams – A filament light bulb Electrical Energy Heat

Sankey Diagrams – An LED Electrical Energy Light Heat LEDs are more efficient than traditional filament bulbs, because a greater percentage of the energy is transferred to light – rather than wasted as heat.

Efficiency Electrical Energy Light 80 J 100 J Heat 20 J 80 J of useful light energy from 100 J of electrical energy. This would be 80% efficient Electrical Energy Light 80 J 100 J Heat 20 J

Efficiency How much useful energy from 100 J of electrical energy? How efficient is this? 4 J ? J 4 % 100 J 17 J 79 J

How much useful energy from 894 J of energy input? Efficiency How much useful energy from 894 J of energy input? How efficient is this? 60 J ? J 6.7% 894 J 103 J 731 J

efficiency =useful energy out (x 100%) total energy in   efficiency = useful power out (x 100%) total power in Wasted energy is eventually transferred to the surroundings, which become warmer. The wasted energy becomes increasingly spread out and so becomes less useful.  

Total Energy In (J) Useful Energy Out Wasted Energy Efficiency (%) 100 6 50 3 75 25 5748 4675 647 354 33 67 40 20

Total Energy In (J) Useful Energy Out Wasted Energy Efficiency (%) 100 6 94 50 3 47 75 25 33 67 5748 4675 1073 81 647 293 354 45 200 40 160 20

How can we improve efficiency?

How can we improve efficiency?

Practicals Filament/LED bulb set-up Lego bricks Candle/torch taped to board