Last updated: 04-11-2011 10:00am.

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    Week of 5/1/2011 --- HW 14 -- LAST HOMEWORK

    1. Mastering Physics. Includes tutorials and book problems 34.15, 17, 20, 29, 33, 35 and 44. The Final test which includes Ch 34 WILL USE some of these problems (and nothing else from Ch. 34). Due Friday 5/6 at 11:55 pm.
    2. Read Chapter 34.
    3. Written Assignment -- Due Friday 5/6/11 (5 pm, my office or physics office):
      • 34.72
      • ALSO: The sun has a diameter of 1.4 million km and is 150 million km from Earth. (On average) The average surface temperature of the sun is 5900 K.
        • (A) You can derive the solar constant (how much energy in W/m^2) the Earth is illuminated with. Completely relevant for understanding weather and solar energy.
        • (B) Using Wien's law and an emissivity of 1 for Earth, you can derive what the average surface temperature of the Earth should be. We are warmer than this because of the greenhouse effect. The "anthropogenic greenhouse effect" is on top of the natural greenhouse effect. Since climate change will dominate your lives, it is worth knowing how to do this fairly simple calculation.


    Prior Assignments


    Week of 4/25/2011 --- HW 13

    1. Mastering Physics. No book problems. Due Tuesday 4/26.
    2. Skim Chapters 34, 35. We won't have time to cover them in depth, but you should find them interesting.
    3. Written Assignment -- Due Friday 4/29/11 (5 pm, my office or physics office):
      • 27.20, 27.24, 27.28
      • 27.30, 27.36, 27.40
      • 27.50, 27.56, 27.59
      • 27.61
      • Problems 50 and 61 will be covered in recitation.
      • ALSO: Explain (with diagrams showing current directions and forces) why the can was crushed in the video.


    Week of 4/11/2011 -- HW 12

    1. Read Chapter 27
    2. Written Assignment -- Due Friday 4/15/11:
      • 26.45, 26.47, 26.52
      • 26.56, 26.69, 26.72
      • 26.74, 26.81, 26.92
      • On page 5 of lecture 30, a problem with units is assigned. Please do it.
      • You did 26.63 online. Repeat the problem and explicitly show the force from the bottom two wires on the top wire. Express your answer as vector components (i-hat, j-hat).


    Week of 4/4/2011

    1. Read Chapter 26
    2. Assignment #11: The assignment begins with tutorial problems and also contains a number of book problems.
    3. The book problems are: 26.19, 26.31, 26.33 26.35, 26.39, 26.63
    4. NOTE: The Online assignment also has an EXTRA CREDIT problem.

    Week of 3/28/2011

    1. Read Chapter 25
    2. Written Assignment #10:

      [Due Friday 4/1/2011 by 5:00 pm in my mailbox - Workman 333]

      • 24.61 Please show all your assumptions and any data you look up online.
      • Custom -- Rework the example problem with 4 resistors from Wednesday class.
      • 25.16
      • 25.20
      • 25.25 Answer is in back of book. Draw the circuit diagram for each of four cases.
      • 25.32
      • 25.38 Show your work (what resistors are in parallel, which are in series?)
      • 25.48
      • 25.49
    3. Mastering Physics HW #10 is posted. It includes the following book problems (as well as tutorial problems). 25.19, 23, 34, 36, 59, 61, 74

    Week of 3/20/2011

    1. Read Chapter 24
    2. The homework this week is on-line only.
    3. Mastering Physics HW #9 is posted. It includes the following book problems (as well as tutorial problems).
    4. 24.14, 17, 19, 21, 23, 25, 29, 31, 33, 35, 57, 59
  • Read Chapter 23

    Week of 3/5/2011

    1. Read Chapter 23
    2. Mastering Physics HW #8 is posted. I recommend you do the tutorial problems first so they can help you w/ the written assignment.
    3. Written Assignment #8:

      [Due Friday 3/11/2011 by 5:00 pm in my mailbox - Workman 333]

      • Look below at Assignment 7. I told you the last problem in which you calculate the potential on a disk was not due till assignment 8 but wanted to give it to you in advance. Now is the time to do it.
      • 23.25
      • 23.33 Draw a circuit diagram is for each configuration you come up with.
      • 23.18
      • 23.42
      • 23.54

    Week of 2/28/2011

    1. Read Chapter 22
    2. The Mastering Physics assignment has been posted -- It's due Friday night. I made it due first because of its tutorial nature. It includes the problems 22.25, 22.27, 22.39
    3. Written Assignment #7:

      [Due Monday 3/7/2011 by 5:00 pm in my mailbox - Workman 333]

      • 22.26
      • 22.29
      • 22.30
      • 22.31
      • 22.41
      • 22.42
      • 22.43
      • 22.50
      • 22.51
      • This last one will be due 3/11. You can start on it now if you want. Derive the potential along the x-axis for a disk with charge Q and radius ``a''. This problem is worked in the book and I will also work it in class. (It's very similar to the solution for Electric field of a disk ... but easier) You may reproduce either derivation, but understand it.


    Week of 2/21/2011

    1. Read Chapter 21
    2. Mastering Physics HW #6 is posted. In addition to the online-only problems there are also 21.22, 24, 25, 35 and 21.37.

      [Due Monday 2/28/2011 at 11:59 pm]

    3. Written Assignment #6:

      [Due Monday 2/28/2011 in class]

      • 20.69 (from last assignment)
      • 21.19 (please note that the apparent blanks in the book should read "+2q and -q")
      • 21.20
      • 21.70
      • In the 2/23 lecture, I give formulae for the E-field outside a sphere of charge, a line of charge, and a sheet of charge. Derive all three formulae using Gauss's law. (This counts as three problems)


      Week of 2/14/2011

      1. Read Chapter 20
      2. Mastering Physics HW #5 is posted. In addition to the online-only problems there are also 20.27 and 20.33.

        [Due Monday 2/21/2011 at 11:59 pm]

      3. Written Assignment #5:

        [Due Monday 2/21/2011 in class]

        • 20.34
        • 20.40
        • 20.43
        • 20.53
        • 20.54
        • 20.59 With the following changes: The particle mass is 0.086 milligrams and has a charge of 4.0 nanoCoulombs
        • 20.69 This one will take a while.

      Prior Assignments


      Week of 2/7/2011

      1. Read Chapter 32
      2. The Mastering Physics assignment has been posted.
        I recommend you start with it because of its tutorial nature.
        MP Also includes the following written problems
        32.11, 32.13, 32.21, 32.37, 32.53
      3. Written Assignment #4:

        [Due Monday 2/14/2010 in class]

        • 32.40
        • 32.48
        • 32.52
        • 32.58
        • 32.60
        • 32.62

      Week of 1/31/2011

      1. Read Chapter 32
      2. Mastering Physics HW #3 is posted It includes the following book problems:
        • 31.28, 31.63, 31.85
        • 31.27, 31.37, 31.49
        • 31.51, 31.84
        • ... And also online-only problems

        [Extended to Tuesday 2/8 at 11:59 pm]

      3. Written Assignment #3:

        [Extended to Wednesday 2/9/2011 in class]

        • 31.39, 31.40 These two problems form a pair (but it counts as two problems). In addition to using equations, GOOD SKETCHES USING PRINCIPAL RAYS ARE REQUIRED for these problems.
        • 31.76 (You will need this result to do problem 84 -- Also, read the hints below.)

          HINT: I could not do this problem the way Wolfson seemed to suggest, so I will assume you cannot either. Here was my approach: The trick with the problem is to figure out what property of a "focus" to use to prove that f = R/2. I used the property that rays parallel to the optical axis all converge to the same point (the focus). I have posted a figure here to give you some guidance In my figure, I show "h", which is arbitrary, and angles alpha, beta, theta and theta'. There are relationships between these angles, and I ask you to find them. Once you have found the relations, you will see the relationship between R and f, and that f=R/2. You will also need the small angle approximation for the tangent function. As I have explained in class, you should use a principle from geometry, trigonometry, or physics that justifies each step in your "proof".

        • 31.82 Here you get to practice your calculus a little. HINT: Calculate df/dn. Then divide by the expression for "f" and multiply both sides of equation by "dn". (Yes ... this is allowed!).
        • 31.82a This is my problem (not in book). It extends 31.82. Using the expression you just derived, calculate the fraction df/f for n=1.5 and dn=0.001. Compare this to what you get by plugging in n=1.5 and then n=1.5001. The two answers should come out quite close to eachother (because calculus works!)


      Week of 1/24/2011

      1. Read Chapter 31
      2. Mastering Physics HW #2 is posted

        [Due Saturday 1/29/2011 at 11:59 pm]

      3. Written Assignment #2:

        [Due Friday 1/28/2011 in class]

        • 30.13 (The answer is in the book. What YOU need to do is do a sketch that justifies the answer, and to justify every ray in your sketch)
        • 30.43 (The answer is in the book. Your work should show how you get the answer. Begin with Snell's law.)
        • 30.52 (This is not a difficult problem if you draw a sketch first to visualize what is happening.)
        • Proof of Snell's law by Fermat's theorem. I will discuss this on 1/24/11 in class.


      Week of 1/17/2011

      • Read Chapter 30
      • Mastering Physics HW #1 is posted.

        [Due Friday 1/21/2011 at 10:45 am]

      • OTHER NOTES: Get clicker, Log-on to MP and do First assignment. All due in class Friday 1/21/2011. Bring note describing technical problems, if any.