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Home Minds On Electric Circuits Mission EC6 P, V, I, R, and Cost Calculations Help Help 10

Mission EC6 P, V, I, R, and Cost Calculations

The Question

What does it cost (in cents) to leave a 2000-Watt electric oven on for 8 hours? Assume that you pay 10 cents for every kilowatt-hour that you use. (Enter your answers to the second decimal place.)
 
(Note: The numbers in this problem are randomly selected and may differ from those above.)

Formula Fix

Mathematically, power is a rate quantity - a time-based quantity. It is the rate at which an appliance transforms electrical energy into other forms of energy. The power (P in Watts) of a light bulb is related to the energy transformed by the bulb (∆E in Joules) and the time (t in seconds) that the bulb is used. These quantities are related by the equation
P = ∆E / t.

Game Plan

The utility company that provides electrical energy to your home will typically charge you on the basis of the amount of electrical energy that is consumed. The unit kilowatt-hour is a unit of energy. Success on this question will involve three steps. First, calculate the energy (in units of watt-hour) used by the appliance during its 8 hours of use. See the equation in the Formula Frenzy section. Second, convert the energy used in watt-hour to units of kilowatt-hour. There are 1000 watt-hour per kilowatt-hour. Third, use the cost per kilowatt-hour to determine the cost in cents. This third step of the question is as easy as determining the cost of buying 13 pieces of candy at 10 cents per piece. You can do it!

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