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Unformatted text preview: terry (ect328) homework 30 Turner (59130) 1 This print-out should have 12 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points Consider a series RLC circuit. The applied voltage has a maximum value of 180 V and oscillates at a frequency of 82 Hz. The circuit contains a capacitor whose capacitance can be varied, a 1000 resistor, and a 3 H inductor. Determine the value of the capacitor such that the voltage across the capacitor is out of phase with the applied voltage by 42 , with V L leading V max . Correct answer: 0 . 73069 F. Explanation: The phase relationships for the voltage drops across the elements in the circuit are shown in the figure. V R V L V C V m a x Let : = 42 , f = 82 Hz , L = 3 H , R = 1000 . From the figure, the phase angle is = 90 - = 90 - 42 = 48 , since the phasors representing I max and V R are in the same direction (in phase). The angular frequency is = 2 f = 2 (82 Hz) = 515 . 221 Hz . We know that X L = L = (515 . 221 Hz) (3 H) = 1545 . 66 and X C = 1 C . From the equation tan = X L- X C R we obtain 1 C = L + R tan , C = 1 bracketleftbigg 1 L + R tan bracketrightbigg = 1 bracketleftbigg 1 X L + R tan bracketrightbigg = 1 515 . 221 Hz 1 1545 . 66 + (1000 ) tan 48 10 6 F 1 F = . 73069 F . 002 10.0 points Consider a series RLC circuit. The applied voltage has a maximum value of 130 V and oscillates at a frequency of 80 Hz. The circuit contains an inductor whose inductance can be varied, a 1100 resistor, and a 1...
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- Fall '09