recitation10-solutions

recitation10-solutions - Recitation 2760 11/4/2008 1. You...

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Unformatted text preview: Recitation 2760 11/4/2008 1. You have a 200 Ω resistor, a 0.400 H inductor, a 6.00 μF capacitor and a voltage source that has a voltage amplitude of 30.0 V and an angular frequency of 250 rad/s. The resistor, inductor, capacitor, and voltage source are connected to form an L‐R‐C series circuit. The current is given by i = I cos ωt , so v = V cos (ωt + ϕ ) . a) What is the impedance of the circuit? b) What is the current amplitude? c) What is the phase angle of the source voltage with respect to the current? d) What are the voltage amplitudes across the resistor, inductor and capacitor? Compare their sum with the voltage amplitude for the source. e) What are v, vR, vC, and vL, at t = 20 ms? Compare vR+vC+vL to v at this instant. f) Construct the phasor diagram for this circuit. 2. A coil draws 15 A when connected to a 220‐V 60‐Hz AC line. When it is in series with a 4 Ω resistor and the combination is connected to a 100‐V battery, the battery current after a long time is observed to be 10 A. (a) What is the resistance in the coil? (b) What is the inductance of the coil? 3. A coil is connected to a 60‐Hz, 100‐V AC generator. At this frequency the coil has an impedance of 10 Ω and a reactance of 8 Ω. (a) What is the current in the coil? (b) What is the phase angle between the current and the applied voltage? (c) What series capacitance is required so that the current and voltage are in phase? (d) What then is the voltage measured across the capacitor? 4. Two AC voltage sources are connected in series with a resistor R = 25 . One source is given by V1 = (5.0 V) cos (ωt – ϕ), and the other source is V2 = (5.0 V) cos (ωt + ϕ), with ϕ = π/6. (a) Find the current in R using a trigonometric identity for the sum of two cosines. (b) Use phasor diagrams to find the current in R. 5. In the circuit shown in the figure on the left, the AC generator produces an rms voltage of 115 V when operated at 60 Hz. What is the rms voltage across points a) AB, b) BC, c) CD, d) AC and e) BD? ...
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This note was uploaded on 06/21/2010 for the course PHYS 2760 taught by Professor Kozstin during the Spring '08 term at Missouri (Mizzou).

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