# Electric Power

## Physical Science - Middle School

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Electrical Power © Copyright NewPath Learning. All Rights Reserved. 94-4491 Visit www.newpathlearning.com for Online Learning Resources. Machines and appliances transform electrical energy into other types of energy. A stove transforms electricity to heat, and a stereo transforms electricity to sound. The rate at which electrical energy is transformed into another type of energy is called electric power. The unit for electrical power is a watt, and the formula is power equals voltage times current. heat sound Electricity: Measurements, Units and Symbols This table is a summary of electric measurements, and their corresponding units, unit symbols and abbreviations in formulas. power (P) = voltage (V) x current (I) 12,000 W = 240 V x 50 A power (P) measured in watts (W) power (P) = voltage (V) x current (I) 12,000 W = 240 V x 50 A power (P) measured in watts (W) Quantity Measurement Voltage E or V volt V Power P wattW Current amp A I R Resistance ohm Unit Symbol Unit of Measure Formula Abbreviation power (P) = voltage (V) x current (I) P = V x I 60 W Quantity Measurement Voltage E or V volt V Power P wattW Current amp A I R Resistance ohm Unit Symbol Unit of Measure Formula Abbreviation power (P) = voltage (V) x current (I) P = V x I 60 W Let’s look at the example of electrical power. If you are referring to the power of a light bulb, then you would use the unit called a watt. You would write 60 watts using a capital W. If you wanted to write out the formula for power, you would use the abbreviation capital P for power. For example, an electric stove top that uses 240 volts and has a current of 50 amps has 12,000 watts of power. A stereo transforms electric power to sound.
Pause and Review Use the formulas to solve the problems. Show your work. Electrical Power © Copyright NewPath Learning. All Rights Reserved. 94-4491 Visit www.newpathlearning.com for Online Learning Resources. 1) A voltage of 120 V is applied to a 60 W light bulb. How much current is in the bulb? 2) A light bulb has .25 A of current using a voltage of 120 V. What is the power rating for this bulb? Power = Voltage x Current 1) A voltage of 120 V is applied to a 60 W light bulb. How much current is in the bulb? 2) A light bulb has .25 A of current using a voltage of 120 V. What is the power rating for this bulb? 1) What is the resistance of an object if a voltage of 20 V produces a current of 5 A? 2) What is the current produced when a voltage of 30 V is applied to an object with a resistance of 6 ohms? Power P wattW Resistance ohm power (P) = voltage (V) x current (I) P = V x I 60 W 1) What is the resistance of an object if a voltage of 20 V produces a current of 5 A? 2) What is the current produced when a voltage of 30 V is applied to an object with a resistance of 6 ohms? Resistance = Voltage Current