Student Activity Packet

Activity #6: Powering Your Home

Rebuilt Waterwheel of Slater Mill.
Courtesy of Slater Mill Historic Site, Pawtucket, RI.

Description

After reading the essay entitled "Water Power," you will gather information about your own energy use, compare it to energy used by an early factory, and record this information on the activity worksheet.

What to do

You can compare how much electrical energy your house, apartment, or school uses with how much waterpower energy an early factory used. Today we measure electrical energy in "watts" and "kilowatts," in the 19th century, millowners used "millpowers" to measure waterpower.

List all the appliances you will count. Check each one to find out how many watts of electricity it uses. Look for a place on the appliance where the model or serial number is listed; often it is a small plate inside the door, on the back, or on the bottom. On that plate or nearby you can usually find the power rating. (If it lists the number of amps, multiply the amps by 110 to get the approximate wattage.)

Here's a list of appliances to get you started:

Entertainment:

television
 vcr

clock radio


Large appliances:

refrigerator
 stove

washing machine
dryer

furnace motor
air conditioner

well pump
hot water heater

Lights



Others...

Total Number of Watts: __________________

The energy company measures energy use in kilowatt-hours. It takes 1,000 watts to equal 1 kilowatt. A kilowatt running for an hour is a kilowatt-hour. A 100-watt bulb running for 10 hours uses 1,000 watt-hours or 1 kilowatt-hour. If you can't find out about energy use at home or school, you can use the following figure:

Two bedroom apartment -- 2,000 watts (with all appliances running)

Questions

  1. If you ran all the electrical using machines in your home for one month, how many kilowatt-hours of electricity would you use? (Hint: add up the watts all the appliances use, divide by your total 1,000 -- that's how many kilowatts you use when you turn on all yourr appliances. If you left them running for an hour, you would use that many kilowatt-hours of electricity. Multiply the number of kilowatts you use in one hour by the number of hours in a month to get the answer.)

    Total number of kilowatts needed to run everything in your home for one month: __________

  2. You don't use all the appliances in your home every minute of every hour. Estimate how long you use each appliance and calculate how many kilowatt-hours your home uses each month.

    Estimated kilowatt-hours used each month:_________________

  3. Look at the electrical meter or the electrical bill to see how many kilowatt-hours your home actually uses in a month.

    Kilowatt-hours used each month: _________________

  4. It costs, on average, about eight cents for each kilowatt-hour. (It varies depending on where you live.) Figure out how much it costs to run an appliance, such as an air conditioner, for one hour.

  5. Note the difference among the following figures:

    • kilowatt-hours needed to run everything for a month.

    • estimated kilowatt-hours actually used.

    • kilowatt-hours billed for.

    Did you over-or underestimate the kilowatt-hours you actually used?

    Most people think they use much less energy than they actually do. How could you lower the number of kilowatt-hours you use?

    Which appliance in your home uses the most energy? Could you get along without it?

    Why would you want to lower your energy use?

  6. It's impressive how much power water can generate. With all machines running, a smaller mill used one millpower which equals 63.5 kilowatts. How many houses or apartments like yours could you run with one millpower, if everyone ran all their appliances all the time? (Hint: divide 63.5 by the number of kilowatts it takes to run all the appliances -- the answer to Question #1.)

    Houses that could be run by one millpower: __________________

    How many houses could be run if everyone ran their appliances an average amount? (Use answer #3 instead of answer #1 and recalculate using the hint above.)

    Houses that could be run by one millpower __________________

  7. Imagine that you're in charge of distributing the power from a waterwheel to several homes, and it's your job to determine how many homes should be allowed to hook up to the power system. What figure (from question 6 above) should you use, and why? Think carefully about what the average figure represents, and remember that many people run appliances at the same times (for example, stoves at dinnertime).

    What are some of the problems of using water power for powering houses? How might you, as the person in charge of power distribution, be able to hook up more homes to the system?

  8. Remember, in the 19th century, only factories used significant amounts of energy. Workers' homes, for example, used no waterpower (or, of course, electrical power). The only source of energy in the home was oil lamps and wood fires. Today, factories and homes, stores and other businesses, all use energy. List some of the results of this enormous increase in energy use.

    Copyright © 1998 The Lemelson Center for the Study of Invention and Innovation, National Museum of American History, Smithsonian Institution. All rights reserved.

    Comments and questions to the Lemelson Center:lemcen@si.edu

    Last Revision: 6/5/98