Calculating the Efficiency of Appliances
Complete the following problems using the GRASS method.
1. How much does it cost to operate a 90 W light bulb for one day if the cost per
kilowatt-hour is $0.08?
2. A kettle was tested for its energy efficiency. Its power rating was 900 W. The temperature of 1.0 L of water increased from 24°C to 48°C in a time of 4 minutes and 30 seconds.
a. Calculate the energy efficiency of the kettle.
b. Why is the kettle not 100% efficient? What happened to the “missing” energy?
