Unit 1: /25 Unit 2: /25 Unit 3: /25 Unit 4 /25 Total /100ssawyer/videos/Additional... · 2020. 5. 11. · Unit 1: /25 Unit 2: /25 Unit 3: /25 Unit 4 /25 Total /100 Name _____ Notes:

COVID Circuits

Final Exam

Spring 2020

Unit 1: /25

Unit 2: /25

Unit 3: /25

Unit 4 /25

Total /100

Name __________________

Notes: Please work on the entire exam on your own. Do not discuss its contents, general approach to problems, or final answers with anyone else. It is open book, open online notes, open LTSpice, open internet. However, this exam is NOT open for discussion with any other person (or circuits intelligent robot). You have until Saturday midnight to complete the exam and upload to Gradescope. Please contact Prof. Sawyer directly if you have any issues uploading the exam before this deadline. You will have choices and short answers. Partial credit will not be given for most of the exam. It is only given when specified explicitly in the problem. Requests for thought process or calculations are to ensure that you are doing more than guessing (an a.-d. process in some problems). Without some explanation of why you chose an answer, and a quick calculation or diagram, even in choosing the correct answer, you will be marked incorrect.

Please sign below: I have not consulted any person or collaborated with anyone to complete this exam. If any signification portion of this exam is found to match with any other student, I will be given an automatic 0 for the entire exam. Further actions due to academic dishonesty may be warranted after discussion with all parties.

�

MUST SIGN OR -100 points....send signed paper to me via email. I'll put a note that I have it and give 100 points back!

Unit 1:

1. (1 pt) In the circuit below, iR10 is found to be negative using the KVL equation on the right. Draw the direction thephysical current flows.

iR10

Currentdirection

right to left

2. (2 pts) In the figure below, write the nodal equation for V1:

V1 V2−

R2Is−

V1 Vs−

R1+

V1 V3−

R3+ 0=

Nodal Eq.V1

3. (3 pts) In the figure below, label each mesh current and find the mesh current equation for Is in termsof the mesh currents.

Isdefinitionequation

i1− i3+ Is=

4. (5 pts) Circle all the true statements about Thevenin's Theorem:

I can use the thevenin equivent circuit to find the current from the original source.

Current, voltage,and power are correctly represented by Thevenin's equivalent. (note was added:for every component of the original circuit).

Thevenin's Theorem can be used for DC, transient, and AC analysis.

Dependent sources require a test voltage or test current to solve for the thevenin resistance.

You can combine thevenin's theorem with superposition to solve a problem with multiplesources.

F

F

T

T

T

5. (5 pts) True of False (Op Amps):

The positive input V+ and negative input V- must be equal in order for an op amp to function. T or F

F comparatorsExplain your answer: ___________________________________________________

The open loop gain (A) is close to infinity for every ideal op amp configuration. T or F

TExplain your answer: _____________________________________________________

You can find evidence that the integrator op amp has a frequency response of 1/s on your crib sheet. T or F

Explain your answer: _______________________________________________________ T Laplacetable

Another name for a comparator is a unity gain amplifier. T or F

Explain your answer: _______________________________________________________ F voltagefollwer

T or FAn op amp with a negative feedback loop more stable than an op amp with a posi ve feedback loop

Explain your answer: _______________________________________________________ Truepurpose

6. (10 pts, partial credit given here) Design blocks: You have a sensor that outputs a DC voltage depending on itsangle rela ve to the ground but has high frequency noise. You want an LED to light up when the sensor output, Vout, is inthe range V1<Vout<V2.” Draw and label high level design blocks (starting with the sensor ending with the LED) as highlevel circuit design steps. They are high level function based blocks. You can also write the type of circuit componentthat corresponds to those functions but is not necessary. (Estimating about 5 building blocks.....)

Sensor

whatever makes sense, many options lpf, comparators, current limiting resistor for LED,LEDif all blocks are high level functions, the current limiting resistor can be left out

Unit 2:1. (3 pts) Which plot corresponds to the voltage Vc(t) with the polarity specified below?

Plot 1 Plot 2

Plot 3 Plot 4

a. Which answer do you choose by intuition? Why? (Must answer)

b. Which answer do you choose by doing a quick calculation or drawing. Stop the calculation at whatever best identifiesthe answer. (Must answer)

c. If you chose to simulate it, show simulation results here. You do not have to simulate this. It is just an inquiry.

Finalanswer

(graded)Plot 1

d. What is your confidence level for your final answer? This answer will not affect your grade for this exam, it is just aninquiry. Marking a 6 when you don't feel that way will not results in any positive or negative effects for this exam. (Mustanswer)

1 2 3 4 5 6Not at allconfident

Reallyunsure

Slightlyunsure

Slightlyconfident

Confident Extremelyconfident

2. (3 pts) Which plot corresponds to the voltage VR(t) with the polarity specified below?

Plot 1 Plot 2

Plot 3 Plot 4


b. Which answer do you choose by doing a quick calculation or drawing. Stop the calcualtion at whatever best identifiesthe answer. (Must answer)


Finalanswer

(graded)None

should go from -5 to 4



Reallyunsure

Slightlyunsure

Slightlyconfident


3. (3 pts) Which plot corresponds to the voltage VL1(t) with the polarity specified below?

Plot 1 Plot 2

Plot 3 Plot 4

will also take Plot 1 but scaled y axis differently

Plot 1 Plot 2

Plot 3 Plot 4


b. Which answer do you choose by doing a quick calculation or drawing. Stop the calculation at whatever best identifiesthe answer. (Must answer)


Finalanswer

(graded)

Plot 2



Reallyunsure

Slightlyunsure

Slightlyconfident


4. (6 pts) Label each pole-zero plot with whether the circuit is second order decaying sinusoid, second order criticallydamped, second order decaying exponential, second order forever oscillating, first order, DC signal or other.

Explain each answer! Make sure to label the diagrams with your explanation. (Must answer)

other DC signalsecond order decaying sinusoid

second order critically damped second order forever oscillating second order forever oscillating

5. (3 pts) What analytical technique would be most appropriate for determining a voltage value in a circuit whose voltagesource has an exponentially decaying voltage in a first-order circuit?

Phasor S-Domain Bode Plot Thevenin

x

6. (3 pts) What analytical technique would be most appropriate for determining the transient voltage value of a component ifthe voltage source has a square wave voltage?

Phasor Diffential Equations Bode Plot Nodal

x

7. (3 pts) S-domain analysis (Laplace) and Differential equations can be used interchangeably. T or F T

Explain: _________________________________________________________

8. (1 pt) Should we spell the plural of zero like "zeros" or "zeroes"? Is there a difference?

Plural of zero noun iszeros.Zeroes is a verb.

Explain: _________________________________________________________

Unit 3:

1. (2 pts) You can use three inductors to physically replicate the function of atransformer. (i.e. if you don't have a transformer you just need three inductors in a T or F F, It is a model. Key words

are "physically" and "build" Circuit isolation is different, mutual inductance and non idealities are different. Inductors aren't perfect and have resistance. BUT because I just wanted to see what you'd write, it is a debateable question, I've accepted T.

tee shape to build the circuit.)

Explain:____________________________________________________________________

__________

2. (5 pts) The solution to Exams immediately after exams are posted by what means?

Piazza Gradescope Email Back Exam Link Sawyer never posts them!x

3. (2 pts) Phasor analysis can be used to analyze circuits with any periodic input. T or F F

Explain:______________________________________________________________________________

4. (2 pts) Phasor analysis can only be used for single frequency sinusiodal circuits. T or F F

Explain:______________________________________________________________________________

5. (5 pts) Draw the "Circuits Tatoo" that Prof. Sawyer mentions in every single unit?

H(s) box input andoutput

This one is from unit 3...only needinput and output and H(s)

6. (9 pts) In the circuit the below the following is known:

V1

R130

R2C1

C2L11.32E-3

1

2

Z3Z2Z1

The power factor for the total circuit is leading. T or F or cannot tell cannot tell

Explain:______________________________________________________________________________

The reactive power for Z2 is negative. T or F or cannot tell

T

Explain:______________________________________________________________________________

The power factor for Z3 is zero. T or F or cannot tell

T

Explain:______________________________________________________________________________

Unit 4:

1. (12 pts) Label the kind of filter these pole-zero diagrams represent. (i.e. overdamped LPF, underdamped BPF, firstorder HPF, none etc.)

(2 poles)

(2 zeros)

_____________________ _____________________ _____________________

_____________________ _____________________ _____________________

Answer Answer Answer

Answer Answer Answer

Explain each answer! Make sure to label the diagrams with your explanation. (Mustanswer for credit)

If explanation is correct and decision aligns give 2 points. If explanation incorrect but decision is correct give 1 point. If no

explanation give 1 point instead of 2. First order LPFunderdamped LPF will also takeunderdamped BPF and none

underdamped HPF

s2

s σ+ jω+( ) s σ+ jω−( )

1

ss + n

s σ+ jω+( ) s σ+ jω−( ) underdamped LPF, will also take underdamped BPF and none

critically damped LPF underdamped LPF

s −n

s jω+( ) s jω−( )nozero

s n+( )2

nozero

s jω+( ) s jω−( )[ ]

2. Filter Design, use the bode plot below to answer the following questions:

(2 pts. each)

This bode can be made with a series of first order circuits (separated by op amps). T or F T if you add gain

Explain: _________________________________________________________

There is a non-inverting amplifer in this circuit. T or F F phase

Explain: _________________________________________________________

T for critically damped and underdamped HPF and LPF, but F is considered it a BPF..explanation

There is no difference between ωo and ωc for this circuit T or F

Explain: _________________________________________________________

T or FI can make this circuit including an underdamped high pass filter

TExplain: _________________________________________________________

(5 pts) Circle the correct value of H(s)

H s( ) 101 10

5

s 1 105

+

2

=H s( ) 20−

1 106

s 1 106

+

s2

s2

3000s+ 1 107

+

=

H s( ) 15−1 10

5

s 1 105

+

s2

s2

2000s+ 1 106

+

=H s( ) 15

1 105

s 1 105

+

s2

s2

2000s+ 1 106

+

=

full credit2 out of 5 points

H s( ) 10s

s 1 105

+

2

=H s( ) 20

1 105

s 1 105

+

2α s

s2

2000s+ 1 106

+

=


b. Which answer do you choose by doing a quick calculation. Stop the calculation at whatever best identifies the answer.(Must answer)


Finalanswer

(graded)



Reallyunsure

Slightlyunsure

Slightlyconfident


Documents

Unit 1: /25 Unit 2: /25 Unit 3: /25 Unit 4 /25 Total /100ssawyer/videos/Additional... · 2020. 5. 11. · Unit 1: /25 Unit 2: /25 Unit 3: /25 Unit 4 /25 Total /100 Name _____ Notes: