1. Power

2. Your Utilization of Electricity Have you ever heard the word Watt before? Have you ever used the word Kilowatt before? When? When a person is speaking in terms of Watts they are generally talking about the amount of energy that they are using.

3. Power Power is a measure of your energy consumption Power is measured in watts You can calculate power using the following formula P = I V P – power (W) I – current (A) V – voltage (V)

4. Example 1 How much current is running through a 100 watt light bulb with a voltage of 120 V? P = 100 w V = 120 V I = ?

5. I = P / V = 100 W / 120 V = 0.83 A

6. Example 2 How much current is required to operate a DVD player that uses 1200 watts of energy and 120 volts?

7. P = 1200 W V = 120 V I = ? I = P / V = 1200 W / 120 V = 10 A

8. The Cost of Electrical Energy Electrical energy is required to operate electrical apparatuses. The cost of electrical energy is calculated using the following formula. E = P t E = amount of electrical energy used in kilowatt-hours P = power (kilowatts) T = time (hours)

9. To calculate the cost to operate an electrical device you need to multiple the amount of energy consumed by the price of a kilowatt- hour. The cost of a kilowatt-hour that we are going to use is 9.11 cents / hour.

10. Example 1 Spencer played his playstation game for 8 hours last weekend. The playstation uses 160 W of energy and the television uses 200 W of energy. Calculate the cost to operate this system.

11. t = 8 h P = 160 W + 200 W = 360 W = 0.36 KW E = ? E = P t = 0.36 KW x 8 h = 2.88 KWh C = E x 9.11 ¢ = 2.88 KWh x 9.11 ¢ = 26. 24 ¢

12. Example 2 Miss Cook uses her 400 W projector for 2 hours each day for 30 days. Calculate the cost to run the projector.

13. t = 60 h P = 400 W = 0.4 KW E = P t = 0.4 KW x 60 h = 24 KWh C = E x 9.11 ¢ = 24 KWh x 9.11 ¢ = 218.64 ¢ = $2.19

14. Example 3 A blender operates using 15 amps of current and 240 V. If the blender is used for 3 hours calculate how much that would cost.

15. P = I V P = 15 A x 240 V = 3600 W = 3.6 KW t = 3h I = 15 A V = 240 V E = P t = 3.6 KW x 3 h = 10.8 KWh C = E x 9.11 ¢ = 10.8 KWh x 9.11 ¢ = 98.39 ¢