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Electric Energy. Measurement, Units, and cost Your Electric Bill Cost to Operate Appliances. Topics. Part 1: Your Electric Bill What Electric Energy is How Electricity is Measured Reading your Electric Bill Part 2: Cost to Operate Appliances Power – Energy - Cost
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Electric Energy Measurement, Units, and cost Your Electric Bill Cost to Operate Appliances
Topics Part 1: Your Electric Bill • What Electric Energy is • How Electricity is Measured • Reading your Electric Bill Part 2: Cost to Operate Appliances • Power – Energy - Cost • Reading Appliance name plates • Calculating the cost to operate appliances
Voltage Current Resistance Load Power Energy Kilowatt Kilowatt - Hour Key Terms
Part 1: Your Electric BillWhat is Electric Energy? • Energy helps us do many things. • Energy is defined as the ability to do work. • Electrical Energy is • Easily convertible to other forms • Easily moveable from one area to another • Not easily stored
Units of Measure • Ohm’s Law: V=IR • Power Law: P=IV • Voltage • Current • Resistance • Time Rate of Energy Usage • Power • Watts = Joule/s • Energy Used • Kilowatt-hours
Part 2: Cost to Operate AppliancesPower – Energy - Cost • Energy consumed: E = P tE =100 W bulb left on for 20 hours = 2 kWH • Cost to Operate: C = E RC = 2 kWH x $0.15 / kWH = $0.30
Calculating the Cost to Operate an Appliance • Power consumed: P = I VA 120V appliance with 2 Amps of current uses 240 Watts of power. • Duty cycle: • The total number of hours that the appliance is on during a typical period of time (day, month, or year).2 hour/day = 2 x 365 = 739 hr/yr • It is sometimes shown as a percentage2 hour/day = 2 hour / 24 hours = 8%739 hour/yr = 739 / 8760 = 8% • Energy Consumed: E = P tE = 240 W x 2 Hr/day = 0.480 kWH/day • Cost to Operate: C = E RC = 0.480 kWH x $0.15/kWH = $0.072 each day • Annualized Cost$0.072 /day x 365 day/yr = $26 / yr