Watt-Rate  Meter
Question: What ways can you and your family use energy more efficiently in your home?

Study Focus: This lesson will introduce students to the Watt-Rate meter by analyzing the differences between light produced from incandescent bulbs and fluorescent bulbs

Skills: Computing, Graphing, Analyzing

Objectives: After completing the activity, students will be able to:

• Observe, record, and interpret data.
• Use charts, tables, and graphs.
• Identify how energy is measured, and read a Watt-rate meter.
• Communicate ways that changing our in behaviors can affect energy consumption.

OR Science Standards
Benchmark 3
Matter
The Dynamic Earth
Forming the Question
CIM/CAM
Matter
The Dynamic Earth
Forming the Question

Materials:

Watt-Rate meter
Supplied light sources
Various electric appliances (include both high and low resistance
items such as hair dryer and radios)
Procedure:
Students will relate to this topic if you are able to make it personal and relevant.  You may start by discussing an event in the news, film, local media, etc. Here are some examples:


1. Discuss some ideas around the topic of work as the physicist thinks of it. If the class has a reasonable concept base you can use it to explore the idea of why electricity is such an important tool and how it can do work for us. This can lead to the topic of how electricity is generated, transported, converted, and to the efficiency of these activities.

2. Introduce students to the Watt-Rate meter.



3. Most will relate to meters they see on their homes or on business buildings. Point out the various parts of the meter and then plug a hair dryer into the provided socket and turn it on. Leave the Dryer on long enough to cause a noticeable change in the dial face, Call for student observations.

Two predicable observations are:

4. So what do the dials and wheels measure?



5. Use handout Number 1 to help students learn to read the Watt-rate meter.

6. A lesson on reading power meters will be done in class. Students will be given Handout #2 to record the reading of their home meter everyday at the same time for one week. Students will make a graph of the daily home meter readings.

7. Handout #3 can be used to help students gain an understanding about the energy use in their homes. Show students labels on a variety of appliances. Caution them about dangers associated with searching for these labels.

8. Invite John Femal from EWEB to give a talk to the class.

Teacher Information

Electricity is brought to a house through a three-wire cable. An electric meter connected to the household circuit breaker or fuse box shows how much electricity is used. The two energized wires bring electricity from the fuse box to power outlets (plug-ins), utility boxes (lighting) and wall switches. Each energized wire is at a voltage of 120 volts relative to ground and 240 volts relative to each other. The third wire, or neutral, is brought to a grounding bar in the circuit breaker box, or attached to a cold water pipe, as well as to all power outlets, utility boxes, and wall switches. Every appliance that is plugged into an outlet also has a ground connection. The appliance ground is connected to the metal or plastic case of the appliance. At each power and lighting outlet no current flows until a lamp or appliance is plugged in and switched on. However, there is always voltage at that point whether current flows or not. It is like a water tap; the pressure is always present although there is no flow until it is turned on.

 


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