Energy Efficiency calculations for year 7 and year 8 students .pptx

Energy efficiency calculations for Year 7 or year 8 students

1. Unit 5: Energy L7: Energy Efficiency Calculations

2. LI: SWBAT define and calculate the energy efficiency SC: I can: Define energy efficiency. Calculate the energy efficiency.

3. Warm-up: Watch a video: What is efficiency and how to calculate it ?

4. What is efficiency Efficiency: is a measure of an energy converter’s ability to provide useful energy.

5. Worked example 1 A kettle can take 140J of electricity to boil. This produces 112J of thermal energy. Calculate the Energy efficiency of the kettle .

6. Worked example 1 (Solution) Step 1: Write down formula Step 2 Put numbers into formula Step 3 Calculate Step 4 Write answer Energy efficiency = Energy output x 100 Energy Input Energy efficiency= 112 x 100 140 LED Light Energy efficiency= 0.8 x 100 = 80% The energy efficiency of the kettle is 80%

7. Worked example 2 Calculate the energy efficiency of these 3 light bulbs and work out which one is more energy efficient. Over 10 seconds, the LED bulb is produces 90J of light from 100J of electricity. The compact fluorescent bulb produces 90J of light from 106J of electricity. The incandescent bulb produces 90J of light from 900J of electricity. LED Bulb compact fluorescent bulb incandescent bulb

8. Worked example 2(Solution) Step 1 Write Formula Step 2 put numbers into formula Step 3 Calculate Energy efficiency = Energy output x 100 Energy Input LED Light Energy efficiency= 90 x 100 100 LED Light Energy efficiency=0.9 x 100 =90%

9. Worked example 2(Solution) Step 1 Write Formula Step 2 put numbers into formula Step 3 Calculate Energy efficiency = Energy output x 100 Energy Input compact fluorescent Energy efficiency= 90 106 compact fluorescent Energy efficiency=0.85 x 100 =85%

10. Worked example 2(Solution) Step 1 Write Formula Step 2 put numbers into formula Step 3 Calculate Energy efficiency = Energy output x 100 Energy Input Incandescent bulb Energy efficiency= 90 100 Incandescent bulb Energy efficiency=0.1 x 100 =10%

11. Worked example 2(Solution) Step 5 compare to see which is more energy efficient and write which is : The LED bulb is more energy efficient. LED Bulb Compact Fluorescent Bulb Incandescent Bulb 90% 85% 10%

12. Independent Tasks Beginning - Worksheet Q1 to 4 Consolidating - Worksheet 5 to 8 Extending - Worksheet 9 to 12

13. Reflection Reflect back on your success criteria; Can you define Energy efficiency? Can you calculate energy efficiency? What have you done well in this lesson? What could you have done better in this lesson?