Introduction

The Energy Story

 Energy Is Born Energy Types Energy Changes Energy Generation

The Energy Problem

 Conservation of Energy Aging of Energy Finite Resources The Oil "Crisis" Energy Pollution Discussion Topics

The Energy Solution

 Conserving Electricity Appliance Efficiency Heating Conservation Renewable Energy

Teacher Guide

 Conserving Electricity When you look on most of the appliances in your home, you will see several numbers, including the volts (v), hertz (hz), and the watts (w). Sometimes you may have to look in the manual that came with that appliance to find these numbers. The main number we need to figure out the energy that that appliance uses is the watts, which is a unit of power. What is Power?

The unit for measuring energy in the metric system is the Joule (J) or a newton meter (N m). The equations for various kinds of energy yield joules, for example:

 or as units

In order to determine the energy used by an appliance, you also need to know how long, or the time, that it was turned on. The unit of the watt is a unit of power, or the energy used per time. The equation for power is:

 or as units

The unit of a joule of energy is a very small amount of energy and therefore the watt is a very small amount of power. While many appliances are rated in watts, it is common to see power measured in kilowatts (kw) or thousands of watts.