1. KEY WORDS RENEWABLE ENERGY CONSERVED DISSIPATED USEFUL WASTED
EFFICIENCY
SANKEY

2. 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

3. 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

4. Energy cannot be created or destroyed

5. 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.

6. 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.....

7. Now swap books and harshly mark your partner’s work

8. 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

9. Sankey Diagrams – A filament light bulb
Electrical Energy
Heat

10. 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.

11. 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

12. 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

13. 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

14. 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.

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

16. 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

17. How can we improve efficiency?

18. How can we improve efficiency?

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