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10 homework FAUSAK, TAYLOR Due: Mar 31 2008, 4:00 am Question 1, chap 31, sect 5. part 1 of 4 10 points The switch in the circuit shown is closed at time t =0. 9 8H 21 V I At what rate is energy being dissipated as Joule heat in the resistor after an elapsed time equal to the time constant of the circuit? Answer in units of W. Question 2, chap 31, sect 5. part 2 of 4 10 points Calculate the rate at which energy is being stored in the inductor at this time. Answer in units of W. Question 3, chap 31, sect 5. part 3 of 4 10 points What is the total energy stored in the inductor at this time? Answer in units of J. 1. Question 4, chap 31, sect 5. part 4 of 4 10 points How long a time does it take the current to reach 90 percent of its maximum value? Answer in units of s. Question 5, chap 32, sect 4. part 1 of 3 10 points A capacitor of 73 F is connected in series to an inductor of 30 mH and to an open switch. The capacitor is rst charged to a voltage of 276 V. The charging battery is then removed, and the switch is closed. What is the maximum charge on the capacb a 2. b 3. None of these a 4. b C R L R C L itor? Answer in units of C. Question 6, chap 32, sect 4. part 2 of 3 10 points 1 What is the resonant frequency of the circuit? Answer in units of Hz. Question 7, chap 32, sect 4. part 3 of 3 10 points What is the maximum current in the circuit? Answer in units of A. Question 8, chap 32, sect 4. part 1 of 1 10 points The impedance from a to b in one of the circuits below is plotted as a function of angular velocity . Impedance S Select the circuit which gives rise to the above plot. a R L C homework 10 FAUSAK, TAYLOR Due: Mar 31 2008, 4:00 am a 5. b a 6. b 8. = 0 Question 9, chap 32, sect 4. part 1 of 3 10 points In the LC circuit below the capacitor is charged to its maximum 34 C while the switch S is open. Then the switch is closed at t = 0. 3 F 4H Q S Find the energy stored in the inductor at the quater of a period of oscillations in the circuit. Answer in units of J. Question 10, chap 32, sect 4. part 2 of 3 10 points T Find total energy at t = . 12 Answer in units of J. Question 11, chap 32, sect 4. part 3 of 3 10 points Consider a new initial condition at t = 0: q0 = 0, I0 = +1.0 A. Let q = qmax cos( t + ), dq I = , qmax where is assumed to be positive. dt Find the new phase angle for this new situation. 1. = 45 2. = 315 E Question 12, chap 32, sect 4. part 1 of 3 10 points L 3. = 180 R C 4. = 135 5. = 270 R L C 7. = 90 6. = 225 2 Consider the following circuit. After leaving the switch at the position a for a long time, move the switch from a to b. There will be current oscillations. L C Sb a R The maximum current will be given by 1. Imax = E 2. Imax = E 3. Imax = C L LC E R L C 1 LC L C 4. Imax = E 5. Imax = E 6. Imax = 7. Imax = 8. Imax E R C E RL E LC = R homework 10 FAUSAK, TAYLOR Due: Mar 31 2008, 4:00 am Question 13, chap 32, sect 4. part 2 of 3 10 points Which has the dimension of time in an LC circuit? 1. [T ] = [L] [C ] 2. [T ] = 3. [T ] = 4. [T ] = 5. [T ] = 6. [T ] = [ L] [C ] [C ] [ L] 1 [ L] [ C ] [ L] [ C ] E C A B L Question 15, chap 32, sect 5. part 1 of 1 10 points 3 The emf E can drive the circuit below at any given frequency. D R At what frequency does the light bulb glow most brightly? 1. both very low frequencies or very high frequencies 2. the frequency = 1 LC [C ] [ L] 1 7. [T ] = [ L] [ C ] 8. [T ] = [ L] [C ] 3. very low frequencies 4. the frequency = LC 5. very high frequencies Question 16, chap 32, sect 5. part 1 of 1 10 points The current in a light bulb is plotted as a function of angular velocity as shown below. Ilight bulb Question 14, chap 32, sect 4. part 3 of 3 10 points Which has the dimension of time in an RL circuit? 1. [T ] = ([R] [L])2 2. [T ] = 1 [ R ] [ L] 2 [ L] 3. [T ] = [R ] [ L] 4. [T ] = [R ] [R ] 5. [T ] = [ L] 6. [T ] = Select the circuit which gives rise to the above plot. 1. None of these 1 [ R ] [ L] 2 C 2. E R L 7. [T ] = [R] [L] 8. [T ] = [R ] [ L] 2 homework 10 FAUSAK, TAYLOR Due: Mar 31 2008, 4:00 am 4 3. E R C L 4. E L C R 5. E C L R Question 17, chap 32, sect 6. part 1 of 2 10 points The primary of a step-down transformer has 250 turns turns and is connected to a 150 V rms line. The secondary is to supply 32 A at 9 V. Find the rms current in the primary. Answer in units of A. Question 18, chap 32, sect 6. part 2 of 2 10 points Find the whole number of turns in the secondary, assuming 100 percent eciency. Answer in units of turns. ... View Full Document