Links Useful to Tuesday, Feb. 28

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.

Python Lesson for Wednesday

Hump Day!!!

Last week Fani was able to show us the importance and huge role of computer programming and simulations in science research. It is essential, and it is now a fact of life that if you do anything in STEM (and most other fields outside of STEM, as well), knowing even the very basics about what a program is, and how to manipulate existing code (not necessarily writing your programs from scratch) is invaluable and, frankly, expected.

We will do a bit of coding in Python throughout the semester, to expose you to this area of work.

The lesson for today is here.

First thing: In the computer lab, log into your student account and open the program Canopy. Do not click on it more than once - it will take several minutes for it to boot up. Canopy is something you can download for free on a home computer, and allows you to write and run your own Python scripts.

Earth's magnetic field articles

Check out a Scientific American article online, as well as a NASA article on reversals. Last but not least, a NASA article about the way the earth's magnetic field is constantly moving around and changing!

From your article notes and the video notes in class, summarize how scientists know all this, especially if there were no scientists around 800,000 years ago when the earth's field last reversed!!

Momentum

We will try to bring back momentum, p = mv, from last year. Keep in mind two of the big things: it is a vector, and it is conserved.

To see WHY it is conserved, check out this video and take good notes.

Then, check out perfectly inelastic collisions that combine momentum with energy conservation, using something called a ballistic pendulum. Again, take good notes since it will help with some homework problems.