Amps Volts Watts

Electricity is priced and sold by the Kilowatt-hour. (kilo-1000)

If you use 1000 watts of electricity for 1 hour, you use 1 kwh

Assume the price of a KwH of electricity is about 8 cents ($.08)

**There will be DIFFERENT PRICES for your homework!

If you run ten 100 watt light bulbs for one hour:

10 * 100 – 1000 watts1000 watts = 1 kwh

1*.08 = $.08 (8 cents)

Assume that you have three 300 watt bulbs on the outside of your house. You turn the lights on at 9:00 p.m. and turn them off the next morning at 7. How much does it cost to run the bulbs through the night?

How long did the bulbs run? From 9 until 7 is 10 hours

How many total watts? 3*300 = 900 wattsWatthours = 10 hrs * 900 watts = 9,000

watthours

9000/1000 = 9 kwh * $.08 = $.72

A 5000 watt clothes dryer will dry a load of clothes in 1 hour. How much does it cost to dry the load of clothes?

5000 watts * 1 hr. = 5000 watthours5000 watthours/1000 = 5 kilowatthours5 kwh * .08 = $.40 (40 cents)

A football field has 36 bulbs rated at 500 watts. The coach turns on the lights at 5:00 p.m. and turns them off after the game at 10:00 p.m.

How much does it costs to run the lights during the game?

36 bulbs x 500 = 18000 watts

Time = 5 hours

18000*5=90000 watthours90000/1000 = 90 kwh900 * $.08 = $7.20