Homework 3



Homework 3: Due Friday 28 January

Project:

  1. Write a paragraph or so giving me some indication of what you might do for your final project. This isn't a binding proposal. However, by the end of the week you should have a good idea of the general direction you wish to pursue. You should also have a preliminary list of references. (20 points)

Calculating Fields:

  1. Consider a long stick of length L with a charge of Q. We are interested in calculating the electric field of this stick at a point P a distance r from the stick. The point P is positioned such that if one were to draw a line from the stick to the point and that line was perpendicular to the stick, the line would intersect the stick at its midpoint. (See Fig. E2.5 for a picture of this scenario.) (30 points total)
    1. Divide the stick into chunks like we did in class. Determine the field at P if the stick is broken up into 1, 2, 4, and 8 chunks. To get numerical values, let L=5 and r = 2. Remember that the electric field is a vector.
    2. Compare the numerical values above with the exact value obtained by using equation E2.19b.
    3. In the limit that r is much much bigger than L, what would you expect the field due to the stick to be and why? Check equation E2.19b to make sure that it behaves as you expect.
  2. E3B.1 (5 points)
Chapter E4:

  1. E4B.3 (5 points)
  2. E4B.11 (5 points)
  3. E4S.1 (10 points)
  4. E4S.4 (10 points) Toaster Physics!!!
Bonus

There are lots of great problems. Here are some you could try.

  1. E2R.1 (A neat and useful geometric trick for calculating fields.)
  2. E2A.1 (Calculus. Shows you a sneaky way to do an integral.)
  3. E2A.2 (More dipole stuff. Uses the binomial approximation.)
  4. E3A.1 (More integration tricks.)
  5. E4R.2 (Chemical Cells.)
  6. E4R.3 (How to figure out how much a car battery weighs without actually weighing it.)



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