Section

  • You are using a computer and the internet right now and so you are using over 100 phenomena from the physics of electricity and magnetism. We will learn about dozens of those phenomena this year. It is an amazing story.

    HW Tue: summarize the Demo of Charge you did on monday, including a sketch.  Show clearly where the electrons moved.

    HW Wed:  hand in lab notes from electron transfer activity in class on Tuesday.  Include a short description of the set up.  You should report how many electrons are lost per second.  It will be a big number.

    HW Friday: Study and learn the opening section before History in Wikipedia for Electricity (it starts "Electricity is the set of physical phenomena associated with the presence of electric charge").  I will give a reading quiz in class.

    For next Tuesday: 16: Q-1, 2, 3, 4,6; summary of scotch tape static; getting to know the static charge physlets, see below.   (your HW for Tuesday is to open the site and make sure you can run the physlets and show me a printout (not hand-drawn) of each of them.)

            http://phet.colorado.edu/en/simulations/category/physics is the site where you can find most of the physlets we'll use in class. You can select "electricity, magnets, and circuits" to get a shorter list. We'll look at "electric field of Dreams" and "electric hockey" first. Play with this for about 5 minutes.

            Points:

    • know what is difference between doing science and studying science
    • Differentiate science and authority-based systems
    • Be able to define/organize the scope of Phys II vs Phys I
    • Be able to generate positive and negative static charge
    • Be able to draw the topics map and fit in electricity
    • Define and characterize charge

  • For Monday: LABOR DAY HOLIDAY

    For Tuesday: 16: Q-1, 2, 3, 4,6; summary of scotch tape static as assigned in class; Getting to know the static charge physlets, see below.   (your HW for Tuesday is to open the site and make sure you can run the physlets and show me a printout (not hand-drawn) of each of them.)

            http://phet.colorado.edu/en/simulations/category/physics is the site where you can find most of the physlets we'll use in class. You can select "electricity, magnets, and circuits" to get a shorter list. We'll look at "electric field of Dreams" and "electric hockey" first. Play with this for about 5 minutes.

            http://www.compadre.org/Physlets/electromagnetism/  this is another useful page, look at the "electric field" list and open "Field-Line Representation of Vector Fields".  This one will require you use IE or Firefox.  Move the charges around.    Toggle between vectors and lines.  In Config B, can you tell which charges are + and -  ?

    (IMPORTANT NOTE: MANY TIMES, IF AN APP OR PHYSLET DOESN'T RUN ON A COMPUTER, IT IS PROBABLY THE FAULT OF THE WEB BROWSER YOU ARE USING.  SO IF CHROME DOESN'T WORK, TRY INTERNET EXPLORER.  IT IS YOUR RESPONSIBILITY TO FIGURE OUT HOW TO WORK THESE PROGRAMS.)

    HW due Wed: 16: Q-7,8 P-1,2,3, 5, 7, 9     Another good link for static charges that you can run on IE or Firefox:    http://vnatsci.ltu.edu/s_schneider/physlets/main/efield.shtml.  try the various charge configurations, and press play to see the little charge move.

    HW Friday: 16: Q-9, 10, 11; P-13, 15

    HW due next Monday: read 16.7, 16.8; do 16: Q-13,14,15; P-23,25,27,29,33 

    quiz next Tuesday : on Coulomb's Law and forces

    Points:

    • Describe when induction will occur and its effects (on conductors and insulators)
    • Describe conduction and induction cases for electroscope practicum
    • Be able to do simple coulomb’s law calculations
    • Be able to apply vector math to do 2-D coulomb’s law problems
    • Know that Coulomb’s law is complete for electrostatics, not complete for electrodynamics
  • HW due Monday: read 16.7, 16.8; do 16: Q-13,14,15; P-23,25,27,29,33 

    quiz Tuesday : on Coulomb's Law and forces, and for this quiz, memorize the value of k

    HW due Wed: 16: p-17a, 31, 57, 32, 41, 55; and Faraday cage lab memo report  

    HW Due Thursday: using http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml (in IE or Firefox) this link, find all positions in all 7 of the Charge Configurations where the E field is zero.  Be prepared to show the class.  If you place the green test charge at this location, it should not move.

    We will conduct the pith ball minilab on thursday in class.

    HW due Friday:  16: p-11, 26, 62 (use kinematics and F)   Write the hypothesis for the lab, and show me the relation for qtotal as a function of d, m, g, k, and q and calculate a value for q on each pith ball.
    Note, data for the lab in J: drive and I will keep posting new notes on Measuring Coulomb's Law in FILES.

    HW due next Monday:  
    17: Q-1-5; P-1,3,5,7,11;   Show me a draft of the report.  This should be typed and all the parts finished.   use this physlet to prove that Work=0 if you move along an equipotential line for any of the Charge Configurations; bring printed page --  http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml  .

    HW due next Thursday:   The complete formal report of Measuring Coulomb's Law is due.   

    Points:

    1. Be able to describe lightning with physics of charge, induction, and ionization
    2. Sketch field lines for 5 basic cases of charge
    3. Relate electric potential to gravity potential
    4. Relate V to E
    5. Relate equipotential lines to contour (topo) map

  • HW due Monday:  
    17: Q-1-5; P-1,3,5,7,11;      use this physlet to prove that Work=0 if you move along an equipotential line for any of the Charge Configurations; bring printed page --  http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml  .

    HW due Tuesday:  Coulomb pith ball numerical calculation due, using the data you obtained in the lab, will be handed in.  Make your calculation clear and readable.
    Draw E-field lines and equipotential lines for each of these:  1).  2 equal positive point charges  2).  2 positive point charges of 1 and 3 q each  3)  a triangle with a negative point charge at each vertex.   4)  a very long line of charge

    HW due Wednesday: Show me a draft of the Coulomb lab report.  This should be typed and all the parts outlined..  
    An equilateral triangle with sides of 2.0m has a point charge of +1mC at each apex.  a) carefully draw the E field lines and isopotential lines.  b) what is E at the center of the triangle?  c) what is V at the center?

    Thursday. RETREAT

    HW due Friday  RETREAT

    HW due next Monday: Gauss's Law: 16: 39, 41,43,47.  Also, show that Coulomb's Law E=kQ/r2 can be derived from Gauss's Law.  (Recall that k = 1/(4πεo)

    HW due next Tuesday, 26 Sep:   The complete formal report of Measuring Coulomb's Law is due.

    Points:

    • Understand Gauss's law, and use it to derive Coulomb's Law for a point charge
    • Be able to describe lightning with physics of charge, induction, and ionization
    • Sketch field lines for 5 basic cases of charge
    • Relate electric potential to gravity potential
    • Relate V to E
    • Relate equipotential lines to contour (topo) map
  • NOTE: for the exam in one week, you need to recall that F=GMm/r2 and how it is applied.  You don't need to memorize the value of G.

    HW due Monday: Gauss's Law: 16: 39, 41,43, 47.  Also, show that Coulomb's Law E=kQ/r2 can be derived from Gauss's Law. -- Recall that k = 1/(4πeo)  YES, we did this in class, so if your notes are neat and legible, show me that.  If not, then write it neatly for me to review.  

    HW due Tuesday, 26 Sep: The complete formal report of Measuring Coulomb's Law is due

    HW due Wednesday: you are off somewhere learning about college.   The study guide is posted.  

    Thursday: 16: Q-22 and P-67. chapter 17: MCQ-1,2,3,4,5,6; p-8, 13  and you didn't show me this, so be prepared.   use this physlet to prove that Work=0 if you move along an equipotential line for any of the Charge Configurations; bring printed page --  http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml 

    quiz: given a charge, you will calculate properties of field or potential.  

    HW due Friday:  Do chapter 16 MCQ 1-13 (all of them); write each of chapter 16 classic problems on a page and make a diagram for each.   Slides for both 16 and 17 will be posted.

    HW due next Monday: Exam 1 in class.  It covers up through section 5 in chapter 17.

    For fun only, use the Davidson physlet to test if you can put the test charge into orbit around a single or multiple negative charges, or can you make the test charge hover in one place?.  (double click to create new equipotential lines) bring in a printout 

    If you're really good, you can show that the particle bounces between the same value potential lines.

    points.

    • Be able to describe lightning with physics of charge, induction, and ionization
    • Name and sketch the 10 main problems for the exam.
    • Sketch what happens to an insulator in an E field
    • Show how to quantify V from a point charge in space
  • some thoughts about repulsive charges:   http://what-if.xkcd.com/140/

    Monday: exam 1.   bring two colors of pencil.

    HW due Tuesday:  17: Q:6,7,8,9; P-2,4,6,10  

    HW due Wednesday: 17:P-15, 17, 19, 21, 23, 25 use this physlet to put the test charge into orbit around a single or multiple negative charges, or can you make the test charge hover in one place?.  (double click to create new equipotential lines) bring in a printout  http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml   

    HW due Friday:  17: Q-10,18; P-35, 37

    HW due next Monday:.17: P-39, 43, 49, 53, 57 

    NEXT TUESDAY: 17:q-11, 12; P-68,69,71,73,74,77 (be sure to consider all positions on the line)  Also, calculate the design for a capacitor to hold 1.0nC using only a AA battery and one two layers of metal separated by a sheet of plastic wrate, report area and separation.

    Next week: capacitor lab introduced.

    goals for this week:

    1. describe how a capacitor works
    2. design a capacitor of a given C by adjusting d and A
    3. be able to describe the role and effect of dielectric materials in a capacitor
    4. be able to describe 6 fundamentals of lightning
    5. describe the energy stored in an electric field and quantify it.
  • HW due Monday:17: P-39, 43, 49, 53, 57    
    We will discuss the lab to be conducted on Thursday and Friday

    Due TUESDAY: 17:q-11, 12; P-68,69,71,73,74,77 (be sure to consider all positions on the line)  Also, calculate the design for a capacitor to hold 1.0nC using only a AA battery and two layers of aluminum foil separated by a sheet of food plastic wrap: report area and separation

    Wednesday:  PSAT for 11th grade

    HW due Thursday: Two groups will perform lab in class .  Your prelab is due as soon as you walk in the lab.

    • This HW you will work on when not doing the lab these two days.
    • 17: P-45, Search&Learn (S&L) p 500: #3 on lightning; and read 18 sections 1-3,
    • show problem 77 a and b using the physlet below, sketch on printout the elevation of the potential as we did in class, bring printout to class;    then do the same for two equal negative charges, bring printout.
    • http://vnatsci.ltu.edu/s_schneider/physlets/main/equipotentials.shtml

    HW due Friday: Your first reading assignment is due for hand in.  You should read and report on chapter 2 of WHNI.  See the handout if you are confused.
    Two more groups will work on the lab, and others will review HW and lab analysis.  bring your computers if you want to work on your lab.

    HW due next Monday: 18: Q-1,2,3,4,5; MCQ-1,3,4,5; P-1,3,5  Look at this physlet: http://phet.colorado.edu/en/simulation/capacitor-lab

  • HW due Monday: 18: Q-1,2,3,4,5; MCQ-1,3,4,5; P-1,3,5  Look at this physlet: http://phet.colorado.edu/en/simulation/capacitor-lab

    HW due Tuesday:  17: P-85, 88, 93 (hint: find the travel time between plates first); also have your data for the lab plotted (each person should have the data and the plots)

    Wed:  Bring a plot of your data as described for parts 1 and 2.  NOTE;  I have attached in files an example of the analysis section for the lab.  You are allowed to cut and paste from this section, and you are free to borrow equations and ideas from it.  I do expect you to understand it and derive your own numbers based on your data.

    Also due Wednedsay: Do these 3 problems below.

    x1: A capacitor of 25mF is charged to 444V.   It is connected to an identical capacitor.  What is the new voltage on each?  They are then disconnected.  What is the final voltage on each.

    x2: A Leyden Jar of capacitance C is connect to a battery with potential V.  It is disconnected from the battery, and then connected to another jar of capacitance 3C.  a. What charge is on each jar?  b. What potential is on each jar?

    x3: A variable capacitor is charged with a given potential.  a. What is this initial charge?  the capacitance is then quadrupled.  b. What is the new charge?  c. what is the new potential?

    Thursday and Friday:   CONFERENCES

    HW due next Monday: Capacitor Lab is due.   

    Goals for this week

    • Show that electrical current, I, is an outgrowth of charge and time.  
    • Understand the parallel of electrical flow and water flow
    •   Be able to describe that V is the potential for work, and I (current) represents real energy expenditure
    •    Show ability to use I = V/R
  • Welcome back.  If any of you wish to know what I reported to your parents/guardians during the conferences, please see me and I'll happily tell you.  If they didn't come to conferences, but you want to know, I'll happily tell you.

    http://www.jpl.nasa.gov/news/news.php?feature=4340 is about a moon of saturn that holds a static charge.  How does it get charged?

    Note: the next Reading Assignment using Chapter 5 of "We Have No Idea" is due Monday, 30 Oct. Start reading.  

    HW due Monday: Capacitor Lab is due.    

    Due Wednesday:  18: Q-6, P-7, 9, 11, 13; Look at physlet for Ohms Law: bring printout of lowest or highest current possible on it.http://phet.colorado.edu/en/simulation/ohms-law

    Due Friday:  18: Q-7,8, 9,10,11; P-23, 27, 29, 31,33    Bring your VOM to class.  This is now part of required materials.

    HW due next Monday: 18: Q-14,15,17,16; P-34,35,37,38,64,69;               

    Goals for this week

    •   Understand the parallel of electrical flow and water flow
    •   Be able to describe that V is the potential for work, and I represents real energy expenditure
    •    Show ability to use I = V/R, P=IR
    • Be able to set up a power-loss problem in transmission lines.
  • HW due Monday: 18: Q-14,15,17,16; P-34,35,37,38,64,69

    Due Tuesday: calculate R (for two lengths), P at burnout, and ρ for nichrome wire from demo on Monday

    HW due Wednesday; 18: P-55, 77, 80

    Due Thursday: If you didn't get 3 points for the Calculations and Analysis section of your Capacitor Lab, your corrections are due Today.

    word of the day: Physic

    HW due Friday: We will have a quiz on Ohms Law and Power in a lightbulb.  

     next Monday: Exam 2 in class

    goals for this week

    1. show how to solve power problems for simple devices in a circuit
    2. show how to solve power problems for transmission from generator/source to user over a wire
    3. derive a short list of classic problems for chapter 18
    4. show that you can measure resistance, current, and voltage with your VOM

    physic     [fiz-ik] 

    noun

    1.a medicine that purges; cathartic; laxative.

    Example:   Do not take a physic before physics class!

  • http://what-if.xkcd.com/16/ is a little Q&A about lightning.  You are becoming experts on lightning, so here's some interesting info.

    is about mass

    HW due Monday: Exam 2 in class.

    Tuesday: 19: Q-7,  P-1, 4,5, 7, 9, 13   In Class: Ohm's Law Minilab: You will measure V and I for some objects and we'll share this data for determining R

    HW due Wednesday:  19:  Q-10,11   P-15, 31,19  Bring VOM for a practicum in class.

    HW due Thursday:  bring Excel plots for V vs. I data for each object in the minilab

    HW due Friday: 1. There is a solid copper cylinder with a net negative charge.   Draw an end view of the cylinder showing 8 E-field lines and 6 isopotential lines wherever they would exist.

    2. A transmission line carries electricity from the power plant to the factory.  Explain in words why power losses in the transmission line are decreased when the transmission voltage is increased.

    3. We have found there is a voltage drop and a power loss across a resistor in a circuit.  Where do those volts go?  Where does the power go?

    4.  Draw the circuit you used in the Ohm's Law minilab.  If the red and black wires you used had significant resistance, would this give you an error in the measurement of R of the object being tested?  If so, would that make R higher or lower than it should be?

    5.  A capacitor with a dielectric has C=33.3 mF and is charged to 444V.  The dielectric is removed by slowly pulling it away.  How much work was required to pull the dielectric?

    HW due next Monday: do these practice problems.  

    6.  I have five 15W (nominal) light bulbs that normally operate at 12V.  I connect them in series.  How many total Watts do they produce?

    7.  Two charges of -q and -3q are on a horizontal line a certain distance apart.   Show the E-field, the isopotential lines, and the V profile plot.  Also mark any positions where E or V could be zero.

    8.  I shoot a proton at 106 m/s directly toward a charge of +2e that cannot move.  How close does the proton get to the charge before it stops?

    9.   Assume we each have 1.0 MΩ of resistance from L-hand to R-hand, through our body.  If the class of 14 formed a ring, holding hands, what would be the measured resistance across one person's hands?  Across 2?  3?

    10.  Looking at the xkcd above, how far can you be from our 15m flagpole and still be safe from a direct lightning strike?  (ignore the building and assume the ground is flat).

    due next Tuesday: the Ohm's Law Minilab.  Turn in the excel table, and make sure it is complete and neat and pretty, with headings, units, and clear descriptions of each row.  Also, include a paragraph commenting on why you think there is a difference between the 3 values for the colored resistor.  Note, you cannot list operator error or some other lame excuse.  Delve into the measurement in some way.  Note, you must talk about the tolerance value for this resistor.

    goals for this week: 

    • show how to solve simple circuit problems with resistors and power source
    • apply kirchhoff rules to solving more complex circuits with multiple power sources
  • HW due Monday: do these practice problems.  

    6.  I have five 15W (nominal) light bulbs that normally operate at 12V.  I connect them in series.  How many total Watts do they produce?

    7.  Two charges of -q and -3q are on a horizontal line a certain distance apart.   Show the E-field, the isopotential lines, and the V profile plot.  Also mark any positions where E or V could be zero.

    8.  I shoot a proton at 106 m/s directly toward a charge of +2e that cannot move.  How close does the proton get to the charge before it stops?

    9.   Assume we each have 1.0 MΩ of resistance from L-hand to R-hand, through our body.  If the class of 14 formed a ring, holding hands, what would be the measured resistance across one person's hands?  Across 2?  3?

    10.  Looking at the xkcd above, how far can you be from our 15m flagpole and still be safe from a direct lightning strike?  (ignore the building and assume the ground is flat).

    due Tuesday: the Ohm's Law Minilab.  Turn in the excel table, and make sure it is complete and neat and pretty, with headings, units, and clear descriptions of each row.  Also, include a paragraph commenting on why you think there is a difference between the 3 values for the colored resistor.  Note, you cannot list operator error or some other lame excuse.  Delve into the measurement in some way.  Note, you must talk about the tolerance value for this resistor.

        practice problems 19: P-81,82

     Wednesday: FINALS START  Good luck.

  • http://answers.yahoo.com/question/index?qid=20081110232651AAiR2nS

    is a handy and quick solution for solver in the TI-89; it gives the example below.

    2x+3y+10z=28
    3x+2y+4z=16
    x+9y+2z=11

    1.) [2nd] custom, or until the f1 on the toolbar is "var"
    2.) f3
    3.) 4
    4.) solve( and , {x,y}) should appear
    5.) type in the following
    solve(2x+3y+10z=28 and 3x+2y+4x=16 and x+9y+2z=11, {x,y,z})
    6.) enter

    The answers are: x=2, y=0.5, z=2.25

  • Wecome to Term 2, where we get to learn magnetism!

    Note: the next Reading Assignment using Chapter 16 of "We Have No Idea" is due Monday, 4 Dec. Start reading  

    HW due Monday: none.  If you are not happy with your final exam score, please come see me

    HW due Tuesday:  read section 19-6; do 19: Q-17, P-49, 50, MCQ 8, 9, 10, 11

    Wednesday: none

    HW Due Thursday:  19: P-72;  Look at Figure 19-48, replace the 990Ω resistor with a 2.0mF capacitor, and calculate the equivalent R of the remaining two resistors, and then plot V vs. t for the capacitor for up to 5τ;  

    HW due Friday:  19: P-69, 73 ; for a simple RC circuit of 1.0 V and 1.0 Ω and 1.0F, plot Vcapacitor for up to 5s;
    And use your VOM to measure the current from the batteries in a battery-powered device, such as your calculator. Report the I, V, and power of the device. 

    do RC minilab in class.

    [Open-note quiz on capacitors and RC circuits.]

    HW due next Monday:  Reading Assignment using Chapter 16 of "We Have No Idea" 
    Part 1 of the RC lab is due: what is R and C for those data and show how you obtained it.  19: Q-15, 16; P-19, 70, 93, in problem 81,  replace the 85ohm resistor with a 25mF capacitor.  Write the complete V and I curves for the capacitor and both resistors.

    Points for this week:

    • Know the risks associated with electricity.
    • Know the safety rules.
    • Master the V and I graphs for RC circuits.
  • HW due Monday:  Reading Assignment using Chapter 16 of "We Have No Idea" 
      19: Q-15, 16; P-19, 70, 93, in problem 81,  replace the 85ohm resistor with a 25mF capacitor.  Write the complete V and I curves for the capacitor and both resistors. 

    HW due Tuesday:   19: Q-18, 20; P-52, 55;  design and sketch a circuit with τ = 1.0 s ; 
             Part 1 of the RC lab is due: what is R and C for those data and show how you obtained it.  

    HW due Wednesday:  COLLEGE VISIT DAY FOR 11TH GRADE        today, Dec 6, is the 230th anniversary of which invention?

    HW due Thursday: 19: P-51, 74, 95.  All four tables will do the RC lab.  You will have 20 minutes on the apparatus, so I'm counting on you to know the procedure.

    HW due Friday:  show me the R and C calculations and results for your lab.   quiz on safety

    HW due next Monday:  NOTE CHANGE OF DUE DATE!   (for15 points) The RC Lab report is due. RC lab (see assignment sheet), ,   Include your Loggerpro data with any line fits you use in the report.

    Schedule: 

    Mon: review your RC minilab data and continue RC circuits
    Tue:  safety/hazards
    Wed: safety
    Thurs: summary, problems, and practice for chapter 19
    Friday: problems, quiz on hazards and safety

    Points for this week:

    • Know and be able to list the risks associated with electricity.
    • Know and recite the safety rules for the lab
    • Master the V and I graphs for RC circuits; be able to draw for 3 types of RC circuits
    •  
  • This section

    HW due Monday:  (for15 points) The RC Lab report is due. RC lab (see assignment sheet): analyze the data you collect on the #1 and #2 capacitors and your group's resistor; calculate R and C as we did in class, and then measure R using your VOM and read the C of the capacitor, and turn in the report; which includes name, date, lab title, analysis section + circuit diagram.  Include your Loggerpro data with any line fits you use in the report.

    Due Tuesday:  You will do a simple circuit practicum in class, which will be due Thursday.   I will build a simple circuit.  You will, as a group, measure V across each resistor, and all currents, using your VOM.  I will assign a person to measure one item, so you need to be ready to use your VOM in this task.  Then, for Thursday, you will show me a schematic of the circuit, each measured value, and using the measured R and V, calculate the I values.  Compare the calculated I to the measured I values.

             this actually works.  Can you explain how?      .

    Due Wednesday: 19: p-21, 22, 58,86, 89  I gave you a new RC circuit to solve; prepare plots of V and I; Count how many GFI outlets are in your home.  Test one by turning it off using the "TEST" button, and verify what part of the house was affected. 

    Due Thursday:  19: P-87,  Practicum circuit lab report.   I need a clean and large schematic diagram of the circuit, with labels on each element, and also show the table of R, V, Imeas, Ipredicted, %diff (of I) for each resistor.

    Due Friday:  If you guys plan it, we can have a party.  is somebody bringing hotdogs?

    Due next year, Tuesday,  2 January 2018: 20: Q-1,2,3; bring VOM to class.   And a reading report on chapter 8 "What Is Time?" of your book WeHaveNoIdea.

    Friday: view video of manufacturing flash memory cards: 

  • MONDAY: NO SCHOOL

    TUESDAY

    WEDNESDAY

    THURSDAY

    FRIDAY

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