1. Electrical Power & Efficiency

2.  I will be able to calculate cost to operate and percent efficiency of various devices.

3.  Electrical Power: The rate at which electrical energy is produced or used.  Measured in Watts (W). Equivalent to 1 Joule / sec. (1 J/S)  Power at your home is measured kilowatt hours (kWh). Use of 1000W of power for one hour.

4. cost to operate = power used x time x cost of electricity  Power used  kW (1kW = 1000W)  Time  hours

5.  What is the cost of running a 60W light bulb constantly for 5 hours if it costs $0.161/kWh?

6.  How much does it cost to operate a 1500W hair dryer to dry your hair 10 minutes a day for 3 days if the cost of electricity is $0.151 / kWh

7.  Efficiency: Comparison of the energy output of a device with the energy supplied.  Certain devices are more energy efficient than others.  How to tell? Look for EnerGuide label on the device (Canada) Look for energy star label on the device (USA)

8.  To calculate the efficiency of a device we use the percent efficiency formula: Where: E OUT is the useful energy output E IN is the amount of energy needed.

9.  A lightbulb requires 150J of energy to produce 125J of light energy. Calculate the percent efficiency of the lightbulb.

10.  A ceiling fan requires 1800J of energy to produce 1345J of output in the form of spinning blades. How efficient is the fan?

11.  I will be able to calculate cost to operate and percent efficiency of various devices.

12.  worksheet!!