OPENING QUESTION: Take a look at the problem on the board... find 2 or 3 items that trip you up, discuss with your group:

 

We're gonna practice more Biot-Savarting (BS'ing) today:

To wit:

Work alone for 5 minutes or so and see if you can find my error in this solution to example 30.2:

If you missed class today, here were my instructions for the next example. The following image is from example 30.3 (PLEASE DO NOT OPEN YOUR BOOK).

The problem is stated as follows:

Consider a circular wire loop of radius a locatd in the yz plane and carrying a steady current I as in Figure 30.5 Calculate the magnetic field at an axial point P at a distance x from the center of the loop.

The book takes what seems to be to be a rather round-about approach... I tried something completely different (without looking at the book as I always do) and the following solution popped out... (please don't check THAT solution until you've worked on it for 30 - 40 minutes)

 

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ANSWER:

<addendum>

well sorta....

I ended up solving for the B field at the center of the loop NOT at point P some distance away (that's what I get for jumping right to the "finalize answer" part of the author's solution, which, apparently, comes after the answer....

But there's a reason for that which we'll learn about tomorrow!