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# 09 elec 11

## on Jan 17, 2012

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## 09 elec 11Presentation Transcript

• Quantifying Electricity: Energy
• Quantifying ElectricityElectric Potential Energy: The amount of energy storedin each Coulomb. Energy is what operates a load.
• Electric Potential EnergySymbol for Energy: EUnit of Measurement: Joule (J).
• ChargeFor example, if we say that it takes 2000 J toheat-up a cup of water, thenE = 2000 J
• Quantifying ElectricityElectric Potential Difference (Voltage): The differencein the amount of energy Coulombs have on both sidesof a source or load.
• Electric Potential DifferenceIn circuits we dont measure total energy. We measurehow much energy is gained or lost across loads or sources.
• Potential Difference AnalogyThe water at the top of the waterfallhas a lot of energy. The higher thewaterfall, the more energy the waterhas.At the bottom of the waterfall,the water has less energy.The voltage across part of anelectric circuit is like the distancethat the water falls.The higher the voltage, the moreenergy the current has.
• Electric Potential Difference A voltmeter is a device that is used to measure voltage in a circuit.Symbol forvoltmeter Voltmeter
• Electric Potential DifferenceSymbol for Potential Difference: VUnit of Measurement: Volt (V).
• ChargeFor example, if the potential differenceacross a light bulb is 120 Volts, thenV = 120 V
• Calculating Electric Potential DifferencePotential Difference = Energy Charge Volt = Joule Coulomb V = E Q Name Unit Symbol Potential Difference Volt V Energy Joule E Charge Coulomb Q
• Try This.(Problem Set Voltage Question #1)A hair dryer has 1.2 × 103 C of charge passing through apoint in its circuit when it is connected to a 120 Vpower supply. How much energy does the hair dryeruse? Answer: 1.4 x 105 J