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Tuesday, April 28, 2015

Magnetism Check List

As the AP exam nears, here is a magnetism check list. Check it out - what do you need to review? Am I forgetting anything? There is also an EM Induction check list.

EM Magnetism Check List

-         Where does magnetism come from?
-         What are magnetic monopoles?
-         Do you know which way magnetic fields ‘flow?’
-         Can you draw magnetic field lines for different arrangements of magnets?
-         Can you use RHR and LHR to determine which way charged particles will get pushed?
-         Can you use F = qv x B and F = Il x B?
-         Why do charged particles go into circular paths when in magnetic fields?
-         Are you comfortable with mv2/R = qvBsinθ?
-         What is a mass spectrometer?
-         What is a velocity selector?
-         How do you calculate the mass of particles in mass spectrometers?
-         When do particles move in spiral/helical paths in B-fields?
-         What are magnetic domains?
-         Why do magnets generally get weaker with heat? When striking or dropping the magnet?
-         Can you define Ampere’s law?
-         Can you use Ampere’s law for long wires? Long solenoids? Toroids?
-         What is current density?
-         Can you find B-fields inside wires with a uniform current density?
-         Can you find B-fields inside wires with a non-uniform density?
-         When and how do you use the curly RHR? Remember this is for the relationship between currents and B-fields those currents create – one is linear, the other circulates
-         How do you conceptually prove currents running through parallel wires in the same direction attract, and in opposite directions repel?
-         How do you find the strength of the magnetic force between wires with currents?
-         Can you define the Biot-Savart law?
-         How do you use B-S for wires with ends and for loops of currents?
-         How do you use B-S for moving charged particles?
-         What is Gauss’s law for a magnet (i.e. the total flux through a closed surface)?
-         What are superconducting magnets?
-         How do we make permanent magnets?
-         What creates the earth’s B-field?
-         How are auroras created at the poles?

-         From chemistry, what are ferro-, para- and diamagnetic materials?

Monday, April 20, 2015

Check out Richard Feynman talking about various subjects!

Had it not been for Einstein, Richard Feynman, in my mind, is likely the genius of the 20th century. Check out a series of videos of him casually discussing different phenomena, all from a conceptual, physical point of view. It is really interesting how he thought about things. Of course, he was then a magician with math, and could take his physical pictures and models and represent them with the math!

Friday, April 10, 2015

Classes on April 13, 2015

For periods 1-2 and 8-9:

Check out the quiz from before break, and talk through anything you may have missed with others in class. Then, check out and take notes on a video on something called the parallel axis theorem. This is a neat 'trick' for finding moments of inertia of objects, where the axis of rotation is NOT the center of mass, without having to do an integral - the only thing you need to know is the 'normal' moment of inertia for an object, where the axis of rotation is the center of mass. This can be useful for trickier problems and situations.

Next, check out an introductory video for simple harmonic motion. Take good notes, since the homework set will be based on the results.

For Periods 3-4:

Check out the quiz from before break, and talk through anything you may have missed with others in class. Then, check out a video (and take notes) of finding the flux via an integral. Next, check out an introductory video for our last type of circuit, where an inductor and capacitor are combined into a LC circuit. The homework set has to do with these two videos, so, again, take good notes. We will pick up on all this Tuesday.

Friday, April 3, 2015

Have a Wonderful Spring Break!

Everyone have a great break, and catch up on sleep to re-energize for the final sprint to the end of the year! You have earned it. And good luck to the WYSE team, which competes at the state finals the day back from break.