2300 Exam 1 Spring 2003 - University of Houston



Name: _____________________________ (please print)

Signature: __________________________

Circle your class time: 4-5:30PM, TuTh 1-2:30PM, MW 8:30-10AM, TuTh

DO NOT OPEN THIS BOOKLET UNTIL INSTRUCTED TO DO SO

ECE 2300 – FINAL EXAM – April 30, 2003

1. This exam is closed book, closed notes. You may use one 8.5” x 11” crib sheet, or its equivalent. You may use any calculator. Turn all cell phones or other communications devices off.

2. Show all work on these pages. Show all work necessary to complete the problem. If you go on to another page, indicate clearly where your work can be found. A solution without the appropriate work shown will receive no credit. Clearly indicate your answer (for example, by enclosing it in a box).

3. Show all units in solutions, intermediate results, and figures. Units in the exam will be included between square brackets. Use appropriate notation for all quantities.

4. Do not use red ink. Do not use red pencil.

5. You will have 180 minutes to work on this exam.

1. ________________/01

2. ________________/10

3. ________________/15

4. ________________/16

5. ________________/15

6. ________________/05

7. ________________/15

8. ________________/24

Total = 101

1) {1 Point} On the front page, circle your class time.

Room for extra work

2) {10 Points} A multi-range voltmeter is shown below. The rated values, or full-scale values, for the analog (or d’Arsonval) voltmeter are shown next to the meter.

A 25[kΩ] resistor is connected between the 50[V] terminal and the Common terminal. The multi-range voltmeter is then connected to an unknown voltage using the Common terminal and the 200[V] terminal.

The voltmeter reads 175[V] on the 200[V] scale. For this case, when that 25[kΩ] resistor is connected to the multi-range voltmeter, find the value for iX.

[pic]

3) {15 Points} Use either the Node-Voltage Method or the Mesh-Current Method to write a complete set of independent equations that could be used to solve this circuit. Do not attempt to redraw or simplify the circuit. Do not attempt to solve the equations.

[pic]

4) {16 Points} For the circuit shown, find the Thévenin equivalent as seen by terminals a and b .

Draw the equivalent circuit, showing terminals a and b on your circuit, and showing the numerical values of the circuit components.

[pic]

5) {15 Points} For the circuit shown, switches SW1 and SW2 have been in position a for a long time.

At t = 0, both switches are moved instantaneously and simultaneously to

position b and remain there.

a) Find the power delivered by the vS2 voltage source, as a function of time,

for t > 0.

b) Calculate the numerical value of the total energy stored in the capacitors

at t = ∞.

[pic]

6) {5 Points} The periodic current iX(t) is plotted here.

The current iX(t) flows through a 4.7[Ω] resistor. Find the average power absorbed by this resistor.

[pic]

7) {15 Points} The circuit shown operates in steady-state. Find the expression for the current iX(t) flowing through resistor R1.

The reference polarity for iX(t) is defined in the circuit diagram.

[pic]

[pic]

8) {24 Points} The circuit shown operates in steady state.

The average power absorbed by the line is 89[W]. The reactive power absorbed by the line is unknown.

The complex power absorbed by the load is [pic][VA].

a) Redraw the circuit in the phasor domain.

b) Find the numerical value of LLINE.

c) Find the numerical value of iLINE(t).

[pic]

[pic]

2) {10 Points} A multi-range voltmeter is shown below. The rated values, or full-scale values, for the analog (or d’Arsonval) voltmeter are shown next to the meter.

A 25[kΩ] resistor is connected between the 50[V] terminal and the Common terminal. The multi-range voltmeter is then connected to an unknown voltage using the Common terminal and the 200[V] terminal.

The voltmeter reads 175[V] on the 200[V] scale. For this case, when that 25[kΩ] resistor is connected to the multi-range voltmeter, find the value for iX.

[pic]

[pic]

[pic]

3) {15 Points} Use either the Node-Voltage Method or the Mesh-Current Method to write a complete set of independent equations that could be used to solve this circuit. Do not attempt to redraw or simplify the circuit. Do not attempt to solve the equations.

[pic][pic]

[pic]

[pic]

[pic]

4) {16 Points} For the circuit shown, find the Thévenin equivalent as seen by terminals a and b .

Draw the equivalent circuit, showing terminals a and b on your circuit, and showing the numerical values of the circuit components.

[pic]

[pic]

[pic]

[pic]

[pic]

[pic]

5) {15 Points} For the circuit shown, switches SW1 and SW2 have been in position a for a long time.

At t = 0, both switches are moved instantaneously and simultaneously to

position b and remain there.

c) Find the power delivered by the vS2 voltage source, as a function of time,

for t > 0.

d) Calculate the numerical value of the total energy stored in the capacitors

at t = ∞.

[pic]

[pic]

[pic]

[pic]

6) {5 Points} The periodic current iX(t) is plotted here.

The current iX(t) flows through a 4.7[Ω] resistor. Find the average power absorbed by this resistor.

[pic]

[pic]

[pic]

7) {15 Points} The circuit shown operates in steady-state. Find the expression for the current iX(t) flowing through resistor R1.

The reference polarity for iX(t) is defined in the circuit diagram.

[pic]

[pic]

[pic]

[pic]

[pic]

8) {24 Points} The circuit shown operates in steady state.

The average power absorbed by the line is 89[W]. The reactive power absorbed by the line is unknown.

The complex power absorbed by the load is [pic][VA].

d) Redraw the circuit in the phasor domain.

e) Find the numerical value of LLINE.

f) Find the numerical value of iLINE(t).

[pic]

[pic]

[pic]

[pic]

[pic]

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