This is a limited subset of the types and difficulties of the questions from the 2013 State Competition.

Transcription

1 This is a limited subset of the types and difficulties of the questions from the 2013 State Competition. It is NOT meant to be all inclusive or complete, or to limit the scope of the 2014 competition in any way.

2 Instructions No cell phones, no smart phones, no computers, no laptops, no web-aware devices, no cameras. Give them to your coach or turn in to a supervisor. Your team may be disqualified if you keep one! Any type of non web-aware calculator is OK. You may use your own meter (DVM). We will instruct you on the MSU supplied equipment, but not on your personal meter. 1. This exam has two parts a theoretical paper-and-pencil portion and a hands-on portion using electronic parts and lab equipment. 2. The competition will run for 45 minutes. You may allocate that 45 minutes any way you wish. You may work together or individually, or a combination of both. 3. Each team will have its own dedicated workstation, parts, and test equipment. 4. The exam sheets may be separated. All answers for the Theory section must be written on the answer sheet in the numbered spaces provided, and only these answers will be considered. Scrap paper is available and must be turned in. All answers for the Lab portion must be on the Lab Sheets. 5. A countdown timer will beep when time is up. All teams must then stop work immediately, collect all papers including scrap, put the answer sheet on top, and wait at their station for a supervisor to inspect for missing parts, and finally staple the papers together.. 6. The point value for each question is shown in brackets, and the Tie-breakers are indicated as well. Tie-breakers count towards the overall score as normal questions, and if necessary, are then used to break any ties. Tie-breakers are not necessarily in numeric order, and are split over both theory and lab portions. By example: 4. <10 T2> Question text Indicates question #4 is worth 10 points, and is tie-breaker #2. Instructions for Theory Portion of Exam a. Numerically correct answers given without correct units will receive ½ credit. b. Assume all numbers given are exact, and give your answer in 3 significant digits. c. Assume all parts are ideal c. Use Engineering Notation or Scientific Notation where appropriate. d. In some places, the letter u has been used in place of the metric micro prefix e. This exam uses conventional or positive current notation. SAMPLE 2 of 8 SAMPLE

3 CIRCUIT LAB ANSWER SHEET School Name: Team Number: Team Member 1: Team Member 2: SCORE: Station Number: RANK: Score Question Answer Score Question A B C D E 9 Score Question Answer Theory Lab-1 Lab-2 TOTAL Score Question A B C D 14 Score Question A B C D 15 E F G Score Question A B 16 SAMPLE 3 of 8 SAMPLE

4 1. <2> Convert 1270 k to megohms. Your answer must be in M. 2. <2 T1> What value resistor would I need to parallel with a 10 k resistor to make an equivalent resistance of 3.6 k? 3. <2 T2> We have a resistor connected to a battery. If we reduce the value of the resistor by 10.0%, the current through it increases by % 5. <5> The charger for my IPod draws 440 ma when connected to my car s battery (12.6 V). If the charger delivers 6.55 V at A to my IPod, what is its efficiency? 6. <5 T5> Looking at the voltage divider: Ra = 1.50 k and Rb = 8.20 k. What should Vin be to get a Vout of 752 mv? 7. <5 T7> You take an initially discharged 0.33 F capacitor and connect it to a 5.7 ma constant current source for 2.5 seconds. What is the voltage on the capacitor? 9. <5 T9> Match the schematic symbols to their most correct number: (Not all numbered items will be used) 11. RC time constant question: <Not simply what is R*C > 13. <5> Which of the following unit expressions are equivalent to volts. Choose all that apply. <Could be any electronic unit, not just volts> SAMPLE 4 of 8 SAMPLE

5 14. <15> In this circuit, please compute: a. <5> Voltage at Va b. <3> Current through R2 c. <2> Direction of the current through R2 (right or left) d. <5 T12> Power delivered by B1 SAMPLE 5 of 8 SAMPLE

6 General Lab Instructions: You will lose credit for the lab portion if you remove any parts from the lab. Make sure to have a supervisor check off your parts inventory before you leave. Measured values will be considered correct if they are within +/- 5% of actual. Enter your answers directly on the Lab sheets in the areas provided. There is no answer sheet. Enter 3 significant digits when possible. You must enter the appropriate units as well. Numerically correct answers without proper units will only receive ½ credit. You may work together or alone. Do not change the current limit setting on the power supply. Notify a supervisor immediately if you are missing parts or have broken equipment. Fluke DVM setup: Make sure it is set on the 20V range (or the DC Current) in the Slow sample mode. Use the solid RED INPUT as +, and the solid Black LO as ground for voltage measurements Use the red 2A input as the + for current measurements. Terminology: V(a) means the signed voltage between Ground and node a V(R2) means the unsigned voltage measured across R2 V(ab) means the signed voltage from node a to node b, with the + meter lead connected to node a and the - lead connected to node b. I(R3) means the magnitude of the current through R3. Partial Table of Component Color Codes Traditional 4-band resistors use the first two digits for the value, followed by the multiplier and an optional tolerance code. Precision 5-band resistors use the same idea, but use the first 3 bands to specify the value, then multiplier and tolerance. Some parts print the numbers rather than use the color code but it is the same idea. So a part with the printed numbers 123 would have a value of 12 * 10^3 or 12,000. OR it might really be 123 the electronics industry is not consistent! Color Digit Multiplier Tolerance Black 0 1 Brown 1 10^1 +/- 1% Red 2 10^2 +/- 2% Orange 3 10^3 Yellow 4 10^4 Green 5 10^5 +/- 0.5 Blue 6 10^6 Violet 7 10^7 Gray 8 10^8 White 9 10^9 Gold /- 5% Silver /- 10% None 9 +/- 20% SAMPLE 6 of 8 SAMPLE

7 LAB PROBLEM #1 <60 Each question is worth 6 points for a total of 60> Build circuit #1 using the provided resistors, breadboard, and jumper wires. You will not use all the available resistors. Use the variable power supply as the power source. You can apply power either via the BNC connector, or via jumper leads, or any other way. We are NOT going to check your circuit for correctness or safety - <Grin> Contact a supervisor if you blow the fuse in the DVM we have extras. There are 10 measurements (a-j) to take. Enter them in the areas provided on this page: Set the power supply to xx.x V +/- 0.2V using the DVM, NOT the meter on the power supply. Log that voltage with 4 significant digits. If the power supply is set incorrectly, all other measurements will be wrong. a. <T4> Power Supply voltage Measure and log the following voltages with 3 significant digits: b. V(A) = c. V(R2) = d. V(C) = e. <T6> V(BC) = f. V(R6) = Measure and log the following currents with 3 significant digits (whenever possible!): g. I(Delivered by Power Supply) = h. I(R4) = i. <T8> I(R5) = See the next question before disconnecting the ammeter! j. Indicate the direction of the current through R5 as drawn on the schematic. Circle answer: Right Left None Circuit # 1 SAMPLE 7 of 8 SAMPLE

8 Lab Problem #2 <40 Points> Use this parts locator to identify the parts. There are 3 test points to show on the schematic. IN, OUT, and ZZ. ZZ is the rightmost lead of R2. 0. Enter the serial number of the circuit board here 1. <20 T17> Draw the schematic of this circuit on the back of this page. You may use a piece of scrap paper if necessary. Label the inputs and outputs (IN, OUT, ZZ) and the component reference designators (R1, C2 ) on the schematic. You do not need to enter the part values on the schematic. 2. <15, 1 points per box> Fill in the missing items in the data table below with the requested information, do not fill in any boxes that are xxx out. Nominal Power Working Value Tolerance Rating Voltage R1 xxx R2 xxx R3 xxx R4 xxx xxx C1 xxx xxx xxx C2 xxx xxx C3 xxx xxx xxx Note: The value of C1 is tie-breaker T <5 T10> For R2, what is its minimum value if it is still in tolerance? R2 (minimum) = SAMPLE 8 of 8 SAMPLE