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Monday, February 22, 2016

Classes, February 22

Periods 1-2, 8-9:

Try to reach consensus on the first NON-uniform current density problem from Friday.  After this, try the five cases on the Progression sheet you should have from last week. These will be collected tomorrow, and it ranges from point charges to Biot-Savart. If anyone needs to watch videos on any of the topics, please do so.

If you have time to spare, you can access online three magnetism simulation experiments on ActivPhysics, at Go to Electricity and Magnetism, and then try 13.4, 13.7, and 13.8.  These are set up like lessons, and we just need to follow along on the right hand side of the web pages. You can write these out in HW notebooks. These will be done over the next week, and should reinforce magnetism concepts with decent visuals, which many have been asking about.

Periods 3-4:

We will start capacitors. Check out how to add capacitors in series and parallel, and then check out circuit analysis for capacitors. Take notes on these, and there are worked examples in the packet on pages 6 and 8. Try the problems on page 7, and we will pick it up tomorrow.

Many thanks everyone...

Sunday, February 21, 2016

Neat Possible Discovery: A 4-neutron state

In Japan, there is evidence for a 'tetraneutron' state, where a ball of four neutrons, with no protons, was part of the products from the high-energy collision of helium-8 with helium-4. Check out this article, which also has a link to the published paper on this finding. There will need to be verification of the discovery, but if true, theorists are not entirely sure how this state arises - it has not been predicted through quantum chromodynamics (QCD), which is the theory of the strong nuclear force. This is not a true atom, since without a positive charge there are no possible electron orbitals, but it is an interesting object with some possible new physics if real. Is there a different 'interneutron force' that we do not understand? Can this be rectified within the present QCD?

Wednesday, February 17, 2016

Python lesson for today!!

Today, Adam will help us look at some real data that is involved in finding possible exoplanets, or planets outside of our solar system and instead orbiting other stars (new solar systems).

To do the lesson, be sure to setup Canopy first, and then go to the lesson here.

Tuesday, February 16, 2016

Classes today

Periods 1-2, 8-9:

Check out videos on Biot-Savart today. In the Production of Magnetic Fields packet from last time, there is a page for Biot-Savart - this is like the Non-Gauss cases for electric fields, where we need to figure out what one moving charge does for its magnetic field, and then sum them up (i.e. integrate).

The first video is for the magnetic fields of point charges. Take good notes on this. The second video is magnetic fields for straight wires with ends.  There is a third video on the magnetic field due to a loop of current (like the Helmholtz coil in the CRT lab last time). Take good notes on these.

This is a lot of information, and we'll process it more tomorrow. Keep track of any questions you come up with. After the videos, take a look at the magnetism quizzam from last time. Solutions are on the website, in the magnetism folder. Start an error analysis on this.

For homework, try Ch 27 #41; Ch. 28 #8

Periods 3-4:

We will take a look at the analysis of resistor circuits. Watch a video on this for series and parallel resistor circuits. This is going to come from results of the labs last week.

Total resistance in series = R1 + R2 + R3 + ...       just add them up
Total resistance in parallel = [ 1/R1  + 1/R2  + 1/R3 ]^(-1)    add up reciprocals of each branch, then flip over the answer

Take notes on all this from the video. There are some examples on page 4 of the packet. See if you can do anything with problems 1 and 2 on page 5. The remaining time in class can be spent completing the two labs from last week. Keep track of all questions that come up for tomorrow.

Thursday, February 11, 2016

Gravitational Waves Discovered with LIGO

The LIGO (Laser Interferometer Gravitational Wave Observatory) experiment has a strong signal for gravitational waves emitted from a binary black hole system that had two black holes actually merge together to form a single, larger black hole. The signal, observed by both LIGO facilities in Louisiana and Washington in September, 2015, matches the predicted signal from Einstein's general theory of relativity. 

This is a big day for astronomers and astrophysicists who have pondered the existence of these waves, predicted by Einstein in 1916, for almost exactly one century. This is a technical marvel of an experiment to detect incredibly weak vibrations caused when a gravitational wave passes through objects and very slightly distorts their dimensions in various ways due to the stretching in space-time. A shout-out to my friend Vicky Kalogera at Northwestern, who is a member of the collaboration.

See a New York Times article here, and read the actual Physical Review Letters paper here!

Wednesday, February 10, 2016

Python lesson for today

Today, Adam will help us look at some real data that is involved in finding possible exoplanets, or planets outside of our solar system and instead orbiting other stars (new solar systems).

To do the lesson, be sure to setup Canopy first, and then go to the lesson here.

Thursday, February 4, 2016

3 Chem-Phys Classes

Watch the two videos we have for details of air friction.

The first video is the 'easier' case of horizontal motion, where air friction is the only horizontal force acting on the object.

The second video is for things that fall, such as sky divers or coffee filters in our lab. The end result is terminal velocity.

Take careful notes of the derivations in these videos. I suggest anyone in trigonometry sit by someone in calculus, especially where the chain rule comes into play on an integral. Also, explain to anyone not in calculus where natural log (ln) comes out. You will be expected to know how to do these derivations in the near future - if you need to replay any part(s) of a video, go for it, or you can watch these any time. We will summarize the math on Monday.

After the videos and notes, you can work on the homework set and/or lab write up.

Have a wonderful weekend!!  :-)