Calendar Update Energy of Charges Intro to Circuits Ohm s Law Analog Discovery MATLAB What s next?

Calendar Update http://www.ece.utep.edu/courses/web1305/ee1305/reso urces.html

P2 FOLLOW YOUR PROBLEM SOLVING FORMAT Determine the kinetic energy (in ev) of an electron traveling at a velocity of 9 x 10 6 m/s if the kinetic energy of the electron is equal to ½ mv 2. Show all units and unit conversions for each of your calculations.

Equations Type of Equation Ohm s Law Resistvity Parallel Resistors Series Resistors 1 Equation V = IR R = ρl A = ρl πr 2 R eq = 1 R 1 + 1 R 2 + 1 R n Req = R 1 + R 2 + R 3 + Rn Power P = IV = V R 1 V = V 2 R 1 = (IR 1) 2 R 1 = I 2 R 1 Voltage Divider v i = v s R i R eq N KCL n=1 I n = 0 Sum of Currents entering node = 0 N KVL n=1 V n = 0 Sum of Voltage Drops around a loop = 0 Kinetic Energy (any particle) Electric Field 1 2 mv2 E = F/q

Other Unit Conversions Ohms Law Voltage (Volt) V A V = IR Capacitance F (Farad) F C/V Frequency Hz (Hertz) Hz 1/s f = 1/ Force N (Newton) N kgm/s 2 F = ma Energy J (Joule) J N m E = F x d Power W (Watt) W J/s P = E/t Potential Potential (Volt) V J/C V = P.E./q Energy Electron Volt (ev) 1 ev 1.6 x 10-19 J Direct Conversions

P3 FOLLOW YOUR PROBLEM SOLVING FORMAT An electron has charge, q, equal to 1.6 x 10-19 coulombs (C), and is experiencing an electric field equal to 5 x 10 11 V/cm. a) Calculate the force on the charge using E = F/q, where E is the electric field and F is the force on the charge. b) Calculate the work (in units of ev) done on the charge if the charge is accelerated a distance of 1 cm. Use the equation W = F x d, where W is the work done on the charge, d is the distance the charge is moved, and F is the force on the charge. Use the following unit conversions: 1.6 x 10-19 J = 1 ev, 1 V = 1 J/C and 1 J = 1 N m. Show all units and unit conversions for each of your calculations.

Intro to Circuit Components LEARN TO RECOGNIZE CIRCUIT SYMBOLS or Source: F. Ulaby, M. Maharbiz, Circuits, 2 nd Ed, National Technology and Science Press, 2013.

Intro to Circuit Components STRAIN GAUGE I CIRCUIT WHICH TWO LINES THAT INTERSECT ARE NOT CONNECTED?

Intro to Circuit Measurements HOW TO MEASURE VOLTAGE Voltmeter (high resistance): measures voltage without drawing current HOW TO MEASURE CURRENT NEVER PLACE AMMETER IN PARALLEL WITH CIRCUIT COMPONENT!!! Ammeter (low resistance): measures current without dropping voltage Source: F. Ulaby, M. Maharbiz, Circuits, 2 nd Ed, National Technology and Science Press, 2013.

Electric Potential -Visualizing Voltage IN ALL OF OUR LAB MODULES, WE WILL BE MEASURING THE CHANGE IN VOLTAGE WHAT IS POTENTIAL OR VOLTAGE? LET S LOOK AT THE SCIENCE What is the difference between Electric Potential (Voltage) and Potential Energy? - We use the equation for Potential Energy to calculate Voltage Visualizing Voltage (or Potential) How is potential energy visualized in this video? What happens to the potential energy of a particle when it reacts to an electric field? - It decreases

Ohm s Law THERE ARE MANY WAYS TO APPLY OHM S LAW AND WE WILL BEGIN EXPLORING THEM IN THIS COURSE. I V = IR (recall unit conversion 1V = 1A ) V Voltage is measured in units of volts (V) I Current is measured in units of amps (A), where an amp is equal to one coulomb/second (C/s) R Resistance is measured in units of ohms ( )

What is current? CURRENT: THE MOVEMENT OF CHARGE (ELECTRONS) THROUGH A CONDUCTOR IF THERE IS CURRENT, THERE IS AN ELECTRIC FIELD!! Charge Movement Charge Notation (Direction) DC vs AC Source: F. Ulaby, M. Maharbiz, Circuits, 2 nd Ed, National Technology and Science Press, 2013.

Ohm s Law OHM S LAW IS LIKE WATER FLOWING IN A PIPE THE PUMP IS LIKE THE VOLTAGE PUSHING THE CURRENT THROUGH THE PIPE THE RESISTANCE IS LIKE HAVING A THINNER PIPE, AND RESTRICTING THE AMOUNT OF WATER GOING THROUGH

Ohm s Law Voltage, Current and Resistance How are resistors used to change current? LET S VISUALIZE OHM S LAW Ohm s Law and Resistance What are some ways that we can increase the current? - Use a smaller resistor - Use resistors in parallel - Use a higher voltage

Key Circuit Analysis Question What information do you need to determine the current flowing through a resistor? A POTENTIAL DIFFERENCE ACROSS A RESISTOR IS REQUIRED IN ORDER FOR CURRENT TO FLOW THROUGH IT!!! THE POTENTIAL DIFFERENCE CREATES AN ELECTRIC FIELD, AND THE ELECTRIC FIELD MOVES THE CHARGE THAT CREATES THE CURRENT. V1 R I = V 1 V 2 R V2 I CURRENT

Electronics Wheel VOLTAGE RESISTANCE CURRENT POWER - LATER Image Source: http://www.sengpielaudio.com/formulawheelelectronics.gif

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

Introduction to Ohm s Law: Example HEADING EE 1305 Name Group #/Lab Date PROBLEM STATEMENT ADD UNIT CONVERSTIONS AND FIGURES A simple circuit with a 5 V source and a 1 k resistor generates a current (I) through the circuit. (a) Use Ohm s Law to determine the value of I. (b) Convert the current in part (a) from A to ma. Equations/Unit Conv Figures/Circuits 10 3 = 1 k 10 3 ma = 1 A V = IR V = A 5V I R = 1k SET UP CALCULATION AND /OR SOLVE FOR DESIRED VARIABLE Calculations I = V R = 5 V 1 k 1 k 10 3 A V = 0.005 A I = 0.005 A 103 ma A = 5 ma INDICATE SOLUTION Solution I = 0.005 A or 5 ma

Introduction to Ohm s Law: Team Exerise (30 pts) HEADING EE 1305 Name Group #/Name Date PROBLEM STATEMENT ADD UNIT CONVERSTIONS AND FIGURES A current of 6 ma flows through the circuit below. If a 12 V voltage supply is used, what value of R (in k ) is required to generate the 6 ma current. Show all units and unit conversions. Equations/Unit Conv Figures/Circuits 10 3 = 1 k 10 3 ma = 1 A V = IR V = A 12V I= 6 ma R =? SET UP CALCULATION AND /OR SOLVE FOR DESIRED VARIABLE Calculations R =? INDICATE SOLUTION Solution R =? One solution from each team will be picked up.

Waveforms Software LOOK AT THE NUMBER OF TOOLS IN THE AD OPEN THE OSCILLOSCOPE Waveforms is the software necessary to display all the measurements into your computer. Waveforms will allow you to create workspaces to measure and test different circuit scenarios. Every function of the Analog Discovery device will be controlled through Waveforms. OPEN WAVEFORMS OPEN THE POWER SUPPLY

Analog Discovery: Tools SCOPE WAVEGENERATOR POWER SUPPLY PATTERNS NETWORK ANALYZER

Analog Discovery: Channels CHANNELS: Output channels 1 Orange (+/-) 2 Blue (+/-) Ground - Black Waveforms Generator - W1/W2 Yellow Power Supply - V+ Red (up to 5V) Wires 0 to 15 Digital wires

Analog Discovery: Oscilloscope Operation Select Instrument Oscilloscope Turn on Screen settings Time Scale (1 min/div to 10 ns/div) Voltage Scale (5 V/div to 100 µv/div) Offset (from scale or manual) Channels 1 and 2 (on or off) Measurements Maximum Average

MATLAB WE WILL USE MATLAB IN THIS COURSE AS A GRAPHING TOOL IN ORDER TO MODEL LAB RESULTS Enter commands in MATLAB to graph data points Enter each data point individually, or Enter first and last data points, and specify the increment between these 2 numbers. (we will do this today) Export data from Waveforms (Analog Discovery) and import into MATLAB Data appears as a matrix with more than 1000 individual points (we will do this next week, and for every module)

MATLAB: Plotting Data V = 5 ; R =100:100: 1000; I = V./R; plot(r, I, b ) hold on Assigns the value 5 to the variable V (the ; symbol prevents the value from showing again on the command window) Sets Voltage values from 0 to 1000V in increments of 100 Calculates current using Ohm s Law for V = 5 V, and for each value of R. Assume V is in volts, R in ohms, and I in amps. Need to use./ instead of just / since R is a matrix Plots the current (I) as a function of resistance (R) using a blue line Allows you to plot more than 1 plot on the same plot area, and to continue working on formatting your graph.

MATLAB: Plotting Data

MATLAB: Adding labels and text gtext( Ohms Law ) This commands will add text to your plot. Type the gtext command and MATLAB will take you to your graph, then allow you to place the cursor where you want the text. You can use the graphing window to add an arrow from the text to the line. Notice that I spelled Ohm s as Ohms -- Because this command contains it is confusing to MATLAB when you add the apostrophe after the m xlabel( Resistance (ohms) ) ylabel( Current (amps) ) The xlabel and ylabel commands place labels on the x- and y- axes. You can also do this from the graphing window using the toolbar.

MATLAB: Graph IS FONT TOO SMALL? LET S FIX THAT.

MATLAB: Graph Select Edit in main toolbar at top and click on Figure Properties Right click anywhere on the figure, select font, and adjust to at least 14. You can also right click on the gtext you added to increase that font as well.

MATLAB: Graph WHAT COMPONENTS SHOULD YOUR GRAPH HAVE? FORMAT? WHAT OBSERVATIONS CAN YOU MAKE ABOUT YOUR GRAPH? HOW WOULD YOU WRITE THEM IN A REPORT?

MATLAB: Graph FIRST TRY: EDITED TEXT:

Success Points MAKE SURE THE HOMEWORK FORMAT FOR EVERY MEMBER MEETS OR EXCEEDS FORMAT STANDARDS

What s Next this week? Will introduce Ethics and Academic Honesty Passive Components (Resistors and Capacitors) MATLAB Polyfit MATLAB Exporting and Importing Data Please bring laptops to all lectures and labs.

What s Next? Will introduce LAB Module I: Angle Sensor setting up report LECTURE Ethics and Academic Honesty Passive Components: Resistors & Resistivity Breadboards: Series Resistors MATLAB: Polyfit MATLAB: Exporting Data from Channel 1 & 2 Please bring laptops to all lectures and labs.

Questions?