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Calculating POWER and Electrical COST. ELECTRICAL POWER. Rate at which energy is consumed or produced Changed into other forms of energy Measured in WATTS (W). Calculations. Formula is P=IV Power=Current x Voltage. P. Units: Power: watts Voltage: volts Current: amps. V. I.
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ELECTRICAL POWER • Rate at which energy is consumed or produced • Changed into other forms of energy • Measured in WATTS (W)
Calculations • Formula is P=IV • Power=Current x Voltage P Units: Power: watts Voltage: volts Current: amps V I
Electrical Energy • Depends on POWER (kW) and TIME (h) • Units are kWh • The amount of electrical energy used in a home depends on the power of the electrical devices in the house and the length of time that those devices are on
Calculating Electrical Energy and Cost • Example: A coffee pot operates on 2 amperes of current on a 110-volt circuit for 3 hours. Calculate the total kWh used. • Step 1: Determine Power (P=VI) • P = 110 Volts x 2 amps • P= 220 watts • Step 2: convert watts to kilowatts • 220 watts/1000 = 0.22 kW • Step 3: Multiply by the hours given in the problem • 0.22 kW x 3 hrs = 0.66 kWh
Calculating Electrical Energy and Cost • What is the cost of using the coffee pot if the cost of energy is $0.15 per kWh? • Step 1: Multiply the kWh by the cost • 0.66 kWh x 0.15 = $0.099