Voltage, Current, Resistance and Power Report Tips

Power in a Circuit Power can be supplied/delivered to a circuit or it can be absorbed by a circuit component. WHAT IS POWER? POWER GENERATED - + - + - POWER CONSUMMED + If power is supplied by a circuit component (battery), the power is negative - CURRENT FLOWING FROM TO + If power is absorbed by a circuit component, the power is positive CURRENT FLOWING FROM + TO PASSIVE SIGN CONVENTION

Power in a Circuit While voltage is related to Potential Energy and is equal to V = IR WHAT IS POWER? The Power is equal to the voltage across a device times the current entering through its positive terminal. or When one joule of energy is required to transfer one coulomb of charge through a device in one second, this produces a rate of energy transfer of one Watt. P = IV The algebraic sum of all power in a circuit must equal zero based on the LAW OF CONSERVATION OF POWER. Sources: Engineering Circuit Analysis, by Hayt, Kemmerly and Durbin,2007 and Circuits by Ulaby and Maharbiz, 2010

Power in a Circuit Visualizing Power WHAT IS POWER

Power Relationships VOLTAGE CURRENT RESISTANCE POWER Image Source: http://www.sengpielaudio.com/formulawheelelectronics.gif

Power = IV: Variables, Symbols, and Units REMEMBER SOME OF OUR VARIABLES AND UNITS VOLTAGE CURRENT RESISTANCE - POWER VARIABLE SYMBOL UNIT SYMBOL UNIT CONVERSIONS VOLTAGE V VOLTS V V = A, V = J/C CURRENT I AMPS A A = C/s RESISTANCE R OHMS POWER P WATTS W W = J/s OTHERS: ENERGY-FORCE-CHARGE-CAPACITANCE VARIABLE SYMBOL UNIT SYMBOL UNIT CONVERSIONS ENERGY E JOULES J J = Nm FORCE F NEWTON N N=kgm 2 /s 2 CHARGE q COULOMB C CAPACITANCE C FARAD F F = C/V

Calculating Power Unit Conversions V 2 R = V2 J VC A V C As Ws J = W (Watts) I V = A V J VC C As Ws J = W (Watts) R I 2 = A2 V A C As J VC Ws J = W (Watts) V = J C 1 Joule is equal to the energy associated with moving 1 coulomb charge through 1 volt of potential Image Source: http://www.sengpielaudio.com/formulawheelelectronics.gif

Calculating Power Where does current flow? 5 V 1 k 1 k WHY DO WE HAVE CURRENT? 500 1 k

Calculating Power Where is there resistance? 5 V 1 k 1 k WHAT DOES RESISTANCE CONTRIBUTE TO? 500 1 k

Calculating Power Where are there a voltage rises? 5 V 1 k 1 k WHAT DOES VOLTAGE CONTRIBUTE TO? 500 1 k

Calculating Power Where are there voltage drops? 5 V 1 k 1 k 500 1 k

Calculating Power Where is power supplied or consumed? 5 V 1 k 1 k WHERE IS POWER POSITIVE? 500 1 k WHERE IS POWER NEGATIVE?

Recall Voltage Divider Method: Can help analyze circuits The voltage divider relates the total voltage to the potential drop across one of the resistors. R eq = R 1 + R 2 I I = V s R eq = V s R 1 +R 2 V s V 1 = I R 1 = V s R 1 + R 2 R 1 = Vs R 1 R 1 + R 2 v i = v s R i R eq V 2 = I R 2 = V s R 1 + R 2 R 2 = Vs R 2 R 1 + R 2 VOLTAGE DIVIDER METHOD VERY POWERFUL TOOL USED TO ANALYZE CIRCUITS!!!

Calculating Power Where is power supplied or consumed? 5 V 0.00066A 0.00133 A 1 k 0.00133 A 1 k 500 1 k 5 V 4 V 1.33 V WHERE IS POWER POSITIVE? 0.002 A 0.00266 A WHERE IS POWER NEGATIVE? 0.002 A 0.00266A (1) Identify voltage values at all nodes using voltage sources and voltage divider. (2) Identify all currents using Ohm s Law

5 V 1 k 3.0 V 1 k (a) Determine the voltages at nodes A, B, C and D. Calculating Power Where is power supplied or consumed? Node A: Node B: Node C: Node D: 500 A B I3 C I1 I2 I4 I5 (a) Determine the currents I 1 I 7. Label each step according to current. Show your work for each calculation. I4 D I6

Module 4: EKG Sensor Objectives READ MODULE CAREFULLY BEFORE LAB THIS WILL SAVE YOU A LOT OF TIME!!! Construct and analyze three types of RC filters. Compare the filter s input and output behavior (amplitude and phase) to the RC time constant. Construct and analyze Bode Plots for each filter to determine the type of filter (low, high or band pass). Construct a circuit that isolates a 1 Hz signal for a 3-wire EKG instrument. Be able to identify low pass and high pass filters in a circuit diagram.

These tips will help you get started: 1. Create a folder for your Intro to ECE Course, and create a folder for each module (1 9). 2. Take notes of each file you save and what the data represents. Your notes will help you to write your report, and you will not need to start from scratch. You will be prompted to take notes in each Module. 3. Make sure you have all items needed for your report at hand: Results (graphs and tables) open on computer or print Research Info in bullet format (easier to collect and interpret) References by author and date (you can add numbers and citations at the end). Ex. The operation of the potentiometer is based on change in resistance as a function of the angle motion [Smith2009].

Template Highlights 1. Font Requirements (12 Font, single spaced) 2. Table Labels, Units, Captions, and References. SET UP EACH TABLE AND FIGURE FOR EACH PROCEDURE/STEP. Table 1. LED Band Gap Data [1] Material Color Wavelength, nm Max. Forward Current, ma AlGaAs Red 660 30 GaAsP Yellow 585 20 GaP Green 565 30

Template Highlights 3. Figure Labels, Units, Captions, and References. Figure 1. Photon Energy as a function of Wavelength for several LED Materials [1]. 4. Legible Text on all graphs and tables. Compare it to your 12 font text in narrative.

Template Highlights 5. Refer to all tables and figures in your narrative. 6. Include all appropriate headings in bold font. See template. Ex. Procedure I: Description 6. For the results section, include subheadings referring back to each procedure in your module handout. 7. Keep report organized, concise and short. 8. Use your own words throughout your report.

Template Highlights 10. You can copy and past the circuits from each module handout, with a citation. See example below. Figure 5: Ultrasonic Sensor Circuit [5] This citation would be included under References [5] Ultrasonic Sensor Circuit, Introduction to Sensors, Instrumentation, and Measurements Course: Module II, [Online document], 2015, 2/9/2018, Available HTTP: http://isim.olin.edu/labs.shtml.

Template Highlights 11. Make sure to follow the citation formal for all references. See example below for online documents. Online Document: [3] Author name(s), title, [Online document], year month day webpage created, [cited year month day], Available HTTP: full internet address. Example: [3] T. Land, "Web extension to American Psychological Association style (WEAPAS)," [Online document], 1996 Mar 31(Rev 1.2.4), [cited 1996 Sept 14], Available HTTP: http://www.nyu.edu/pages/psychology/weapas.

Organization of Information It will be easy to put your report together if you do the following: 1. Set up template for the Module coming up. 2. Collect your research before arriving to your lab by using the techniques described in the previous section. 3. Take notes on the data you gather, and label each by the procedure and step number indicated on the module handout. Ex. Procedure 1: Step 1. 4. Collect all the required information needed for each citation (Author, Title, Year, etc ) as you read your research information. Create the shorthand notation for each reference (AuthorYear). You can write the complete reference at the end very quickly if you do not need to go searching for the reference information again. 5. Be careful in preparing your first couple of reports, paying attention to detail. After a couple times of practice, you will begin to follow the procedure almost automatically.

Tips for writing 3. Start with the TEMPLATE and erase all the extra information. 4. Add the appropriate HEADINGS and SUBHEADINGS. 5. Write your INTRODUCTION based on your research. Make sure to complete your research step before beginning to write. 6. Write your RESULTS using ACTION sentences. Avoid the use of any contractions. Ex. Didn t, Wouldn t, Can t, etc. 7. AVOID the use of first person. Ex. I noticed that the Voltage increased as a function of Angle. The voltage increased as a function of angle. 8. Add the correct FIGURE and TABLE captions. Make sure all variables include UNITS. 9. Make sure you have all the CITATIONS in order. Your first citation in your report should begin with [1], and increase in number as you read through your report. 10. After your draft is complete, run the SPELL CHECK. 11. After a day has passed, REVIEW/EDIT your draft again.

Lab Report Rubric LAB REPORT RUBRIC LINK Used by TAs to grade report. Include a copy of the rubric with your report every week. Use the rubric to grade yourself before you turn in your report.

Examples of good and bad reports GOOD REPORTS Refer to your figures and tables in your text. Provide descriptions of your data. What is it? How did you collect it? Why does it behave that way? Make all font for figures and tables large enough to read. Make headings distinctive. BAD REPORTS Missing part of Abstract and/or Intro Missing data (Tables/Figures) Missing explanation of data Format not followed for Figures/Tables. Cannot read data, figures, graphs.

Success Points SUCCESS POINTS: TRY TO FIGURE OUT YOUR GRADE AS OF TODAY? WHAT INFORMATION DO YOU NEED AND WHERE CAN YOU GET IT?

Homework P7 and P8 + Problem An electron has a velocity of 4.80 x 10 5 km/s. a) Determine the kinetic energy of the electron assuming the mass of the electron is 9.11 x 10-31 kg. b) If work is done on an electron, and we assume the energy associated with the work is equal to the kinetic energy from part (a), determine the force on the electron if this force moves the electron a distance of 5 mm. c) Assume the electron in part (b) is affected by an electric field and that the force of the electric field is equal to the force calculated in part (b). Determine the magnitude of the electric field if the charge of the electron is assumed to be 1.6 x 10-19 C.

What s Next in Week 4? Will introduce LAB Module IV: EKG LECTURE Quiz 3 Ohm s Law Power con t Intro to Op-Amp NO CLASS ON WED JULY 4 TH Please bring laptops to all lectures and labs.

Questions?