302, EE Introduction to Electrical and Computer Engineering - Honors Dr. Archie Holmes, Jr. Exam #2
Name: _________________________________________________________________ EID: ________________
Please remember....
Read the entire exam before starting All answers must include units and an appropriate number of significant figures If you feel you need more information than is given, please ask!!! Show all work for credit!!! All final answers MUST BE placed in the space provided; work can be on a separate page. Relax!!!
PROBLEM #1: NODE VOLTAGE AND MESH CURRENT EQUATIONS (20 POINTS)
Use the circuit below when answering this question
The possible variables in the circuit above areVA, VB, IA, IB, and IC.
B B
a) Using the labels provided, write the node voltage equations for this circuit in standard form. Only include those node voltages that you need to solve for. b) Using the labels provided, express the power being absorbed by resistor R5 and the power being absorbed by voltage source V1 (i.e., the power will be positive if power is being absorbed). c) Using the labels provided, write the mesh current equations for this circuit in standard form. Only include those mesh currents that you need to solve for. d) Using the labels provided, express the power being absorbed by resistor R5 and the power being absorbed by the current source (i.e., the power will be positive if power is being absorbed). Use the next page as needed. Clearly BOX in your final answer for each of the questions.
PROBLEM #2: CIRCUIT ANALYSIS I (30 POINTS)
*** THIS PROBLEM HAS TWO PARTS AND SPANS 6 PAGES ***
a) Use either Node Voltage Analysis or Mesh Current Analysis to determine the power being absorbed by resistor R5 in the circuit above. Use the following values in your calculations: V1 = 150 V, V2 = 74V, V3 = 100 V, V4 = 191 V, V5 = 15 V, V6 = 23 V, R1 = 3, R2 = 4, R3 = 8, R4 = 5, R5 = 6, and R6 = 7. Another copy of the circuit appears on the next page. In order to receive the 90% of the points for problem, you must do the following: Clearly define which method is being used Label your node voltage or mesh currents clearly in the circuit Write the appropriate set of equations in standard form using the variables names you defined. Your equations must have no numbers in them. Write expressions for the power of the elements in the table below in terms of the variables you defined.
If you chose not to do the above, you will only be evaluated on whether your final answer is correct (i.e., no partial credit). However, you must show your work to get any credit. Element Resistor R5 Expression for Power Value in W
b) Use the method NOT USED in (a) to determine the power being absorbed by resistor R5. Use the following values in your calculations: V1 = 150 V, V2 = 74V, V3 = 100 V, V4 = 191 V, V5 = 15 V, V6 = 23 V, R1 = 3, R2 = 4, R3 = 8, R4 = 5, R5 = 6, and R6 = 7. Follow the rules stated in part (a) to get 90% of the points for this part of the problem. Element Resistor R5 Expression for Power Value in W
PROBLEM #3: CIRCUIT ANALYSIS II (15 POINTS)
Determine the power being generated or absorbed by dependent source in the circuit above. Use the following values in your calculations: = V1 20 V, V2 = 50 V, V3 = 38 V, = 3, R1 = 18 , R2 = 10 , and R3 = 4 . Another copy of the circuit appears on the next page. In order to receive the 90% of the points for problem, you must do the following: Clearly define which method is being used Label your node voltage or mesh currents clearly in the circuit Write the appropriate set of equations in standard form using the variables names you defined. Your equations must have no numbers in them. Write expressions for the power of the elements in the table below in terms of the variables you defined.
If you chose not to do the above, you will only be evaluated on whether your final answer is correct (i.e., no partial credit). However, you must show your work to get any credit. Element Circle the Appropriate Value Expression for Power Value in W
Dependent Source delivered absorbed
PROBLEM #4: CIRCUIT ANALYSIS III (15 POINTS)
Determine the power being generated or absorbed by dependent source in the circuit above. Use the following values in your calculations: V1 = 100 V, V2 =48 V, V3 = 112 V, = 11 , R1 = 10 k, R2 = 4 k, R3 = 2 k, R4 = 6 k, and R5 = 8 k. Another copy of the circuit appears on the next page. In order to receive the 90% of the points for problem, you must do the following: Clearly define which method is being used Label your node voltage or mesh currents clearly in the circuit Write the appropriate set of equations in standard form using the variables names you defined. Your equations must have no numbers in them. Write expressions for the power of the elements in the table below in terms of the variables you defined.
If you chose not to do the above, you will only be evaluated on whether your final answer is correct (i.e., no partial credit). However, you must show your work to get any credit. Element Circle the Appropriate Value Expression for Power Value in W
Dependent Source delivered absorbed
PROBLEM #5: REMOTE TEMPERATURE MEASUREMENT SYSTEM DESIGN (20 POINTS)
Our company, Holmes Electronics Inc., has been hired by a company to create a remote temperature measurement system. A previous employee of the company did the initial design which appears below.
This circuit uses a thermistor, which is a sensor whose resistance changes linearly as a function of temperature. The thermistor is denoted by RT in the circuit and has a value of 250 at 0C and a value of 80 at 50C. This circuit is being used in an application where the environment which has a nominal temperature of 25C. The temperature of the environment is inferred from the voltage from a voltmeter, which is represented by the resistor RM. The value of RM is 10 k. (a) Determine the value of RX needed to makes sure that the voltage measured (VM) is zero at the environment's nominal temperature. (b) If the system now measures a voltage of -1.5 V, what is the corresponding temperature? Use the result from part (a) in answering this question. Bonus (5 points): Our client has returned and wants the value of the measured voltage to be 3 V when the temperature is 50C. What value must the voltage source be made to meet this new criteria?
She has now left the company due to the poor pay and benefits package we offer...