SG_Chap21

# SG_Chap21 - Chapter 21 Alternating Current Circuits and...

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1 Chapter 21 Alternating Current Circuits and Electromagnetic Waves 21.1 Resistors in an AC circuit DC circuit batteries as the power source V = constant (e.g., 1.5V) AC circuit ac power source (generators) V = V max sin(2 ft) It changes with time t f is the frequency (60 Hz in the US, Canada and a few other countries) V rms = I rms R V max = I max R i R =v R R R is a constant for all frequencies Power and RMS values The direction of the current has no effect on the behavior of the resistor The rate at which electrical energy is dissipated in the circuit is given by The rms current is the direct current that would dissipate the same amount of energy in a resistor as is actually dissipated by the AC current The average power Ohm’s Law for a resistor, R, in an AC circuit – ΔV R,rms = I rms R 2 iR max max 0.707 2 rms I II 2 av rms IR V rms = I rms X C , or I rms = V rms /X C X C : Capacitive Reactance fC X C 2 1 Unit: ( ) 21.2 Capacitors in an AC circuit v lags i by 90 o Early

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2 21.3 Inductors in an AC circuit V rms = I
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## This note was uploaded on 03/30/2009 for the course PHY 102 taught by Professor Luo during the Spring '08 term at SUNY Buffalo.

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SG_Chap21 - Chapter 21 Alternating Current Circuits and...

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