Happy Tuesday, one and all!

**For Periods 1-2, 5-6, 8-9:**
It is time to start digesting Biot-Savart for magnetic fields, due to real wires. Unfortunately, real wires do have ends, and this means Ampere's law does not always give a good enough approximation for one's needs. Check out two videos that will take you through

B-S for straight wires with ends, and one for

a loop of wire with a current flowing (like the Helmholtz coil we used in the CRT lab last time).

Note that there is another video showing

an example of B-S with multiple wires and currents, where we try to determine the B-field at some point from the two wires. If you need a review of B-S for moving point charges, there is a

video for this here.

After watching the first two for wires, see if you can figure out the practice problems: Ch. 28 #59,60 for point charges (on page 7 of packet), and the collaboratives for wires on page 9 of the packet.

**For Period 3:**
Let's check out one video on

defining the electric field some more. Take good notes on this since it will help with some of the problems we have coming up. Then, a second video will get into some examples of

how to work with our formula for the electric field, E = kQ/r^2; you should take good notes on this one, too.

We will come back Wednesday and take a look at some examples of finding electric fields, and also electric potential, which is what we will call voltage.

We will try chapter 21, #66, 67, and 69; copies of these are in the packet you receive today.