1. Week 4 Lesson 1 POWER and Energy

2. P = I x V Power = Current x Voltage Voltage = Potential Difference

3. Pee on the Ivy P = I x V

4. Power is... Power = Energy / Time...the rate of doing work

5. The Watt 1 Watt = 1 Joule transferred in 1 second Power (W)= Energy (J) / Time (s)

6. DevicePower Rating (Watt) Time (sec)Energy (J) Kettle 2400 180 Energy = Power x Time Energy = 2400W x (180s) Energy = 432000J 432000

7. Hair straighteners: 60W Electric Cooker: 10kW Fridge: 50W Freezer: 300W Washing machine: 500W Dishwasher: 1300W

8. Hair straighteners: 60W. 15mins Electric Cooker: 10kW. 45mins Fridge: 50W. 24hours Freezer: 300W. 24hours Washing machine: 500W. 1 hour Dishwasher: 1300W. 45mins

9. DevicePower Rating (Watt) Time (sec)Energy (J) Electric Cooker 10000270027000000 Fridge50864004320000 Freezer3008640025920000 Washing Machine 50036001800000 Dishwasher130027003510000

10. Total energy use in one day: 63036000J or 63 million and 36 thousand Joules and Total Energy for 3 months: 5673240000J or 5 billion, 6 hundred and seventy three million, 2 hundred and forty thousand Joules!

11. The Kilowatt Hour = the energy transferred when a power of 1kilowatt (1000W) is used for 1hour.

12. The kilowatt hour (kWh) = 1000W x (60 x 60s) = 3600000J

13. Number of Kilowatt hours used = Energy used (J) Energy in a kilowatt hour (J) or Power (kW) x Time (h)

14. Kettle: 2400W 3mins Energy = 432000J 432000J/3600000J = 0.12kWh 2.4kW x (3/60) = 0.12kWh

15. 1 kilowatt hour costs 12p How much did you earn running up the tower?

16. You generated 3300W in 66s Number of Kilowatt hours used = Power (kW) x Time (h) 3.3kW x (66/3600s) = 0.06kWh 0.06kWh x 12p = 0.7p

17.  P = IV  Power is the rate of doing work. P = Energy/Time  1 Watt = 1 Joule per 1second  1 kWh = 3600000J or the energy used by a 1000W device in 1 hour  Number of Kilowatt hours used = Power (kW) x Time (h)

18. Homework ! Power/kWh and energy : Write down Summary of the lesson Due this Friday !