ch21notes - , SI unit: henry (H) IMPEDANCE Z RESISTANCE R...

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Chapter 21 Notes College Physics by Giambattista et al. John B. Ross, Ph.D. IUPUI Physics Dept. Basic AC Circuits INPUT ac voltage E ( t ) = E m sin ωt OUTPUT ac current i ( t ) = I m sin ( ωt φ ) E ( t ) E m 0 t T 2 T E m How does the current compare with the driving voltage (emf)? Peak is reduced by Ohm’s Law for ac circuits: I = E / Z Waveform is shifted by a phase angle φ : –90° φ ≤ +90° Root-Mean-Square Value a type of average related to standard deviation 2 peak rms Ohm’s Law: V rms = I rms Z or V m = I m Z Power Law: P av = I 2 rms R or P av = ½ I 2 m R Components of Basic AC Circuits : 1) Resistors – cause heat to dissipate but do not introduce a phase shift 2) Capacitors – store charge, impede low frequencies, adds (–) phase shift 3) Inductors – store current, impede high frequencies, add (+) phase shift Inductors are coils, rated by their inductance L
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Unformatted text preview: , SI unit: henry (H) IMPEDANCE Z RESISTANCE R REACTANCE X CAPACITIVE X C INDUCTIVE X L C X C 1 L X L f 2 Ohms Law: V R = IR V C = IX C V L = IX L Chapter 21 Notes College Physics by Giambattista et al. John B. Ross, Ph.D. IUPUI Physics Dept. Phase Diagram : X L +90 R 0 X C 90 Resonance phenomenon found in a variety of physical systems discuss pumping legs on swing, cracking glass with sound, musical instruments, Tacoma Narrows Bridge in Wash. What happens when the driving frequency equals ? Maximum current Minimum total impedance Current in phase with driving voltage Maximum power transferred from source to circuit X L = X C LC 1...
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This note was uploaded on 12/01/2010 for the course PHYSICS 21900 taught by Professor Rhoads during the Spring '10 term at IUPUI.

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ch21notes - , SI unit: henry (H) IMPEDANCE Z RESISTANCE R...

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