This comes to us thanks to Marc B., a former student who loved magnetism and still spends (too much, in his words) time watching anything he finds on the topic. It is perfect for us since we are wrapping things up with magnetism! Check it out! By the way, the website for the polymagnets company, which custom designs magnets with any configuration, is here.
Monday, March 28, 2016
Monday, March 21, 2016
Sir Ken Robinson on Creativity (or the lack thereof) in Schools
This is one of my favorite TED talks. Keep in mind creativity and innovation are two of the most important 'skills' or qualities students need to develop in this globalized, technological economy. Let me know what you think!
A few interesting EM induction examples
As we study electromagnetic induction, a developing technology application is wireless charging, which can go by the name of wireless power or inductive charging. This process uses electromagnetic fields to induce charge in devices, so there is no need for physical contact (hence the use of 'induction'). Presumably this would need to make use of AC currents, in order to cause changes in flux (and apply Faraday's law of em induction).
How do inductive stoves work, where the stove would not necessarily be warm/hot to the touch, but put a copper pot on it and the pot heats up rapidly?!
Another famous example is an electromagnetic pulse, or EMP. These are bursts of electromagnetic energy, and many phenomena can produce such bursts, from lightning to solar flares to nuclear blasts. These can cause damage to electronics systems, for instance, since currents will be induced in circuitry.
Think about where else there could be induction phenomena in your life!
How do inductive stoves work, where the stove would not necessarily be warm/hot to the touch, but put a copper pot on it and the pot heats up rapidly?!
Another famous example is an electromagnetic pulse, or EMP. These are bursts of electromagnetic energy, and many phenomena can produce such bursts, from lightning to solar flares to nuclear blasts. These can cause damage to electronics systems, for instance, since currents will be induced in circuitry.
Think about where else there could be induction phenomena in your life!
Friday, March 18, 2016
For Classes on March 18
Happy Friday everyone!
Periods 1-2, 8-9:
Yesterday you saw something on Faraday's law for a moving hoop/changing area example. This is the case where induced voltage = B dA/dt. Today extend on this by looking at cases where a second force is trying to push a circuit through magnetism, such as dropping a metal hoop into a B-field. What you will see is that, because this process depends on speed, it ends up looking a lot like air friction and terminal velocity from last year! Weird, but true. Remember the case of you trying to swing the metal hoop through the big magnet, and you felt the forces on it trying to slow it down (this is a magnetic brake). Take good notes so you can try to make sense together of the home work problems - see if you can complete things before leaving.
Homework set:
The glider problem on page 6 is based on yesterday - use the notes on page 2 and 3, could be helpful
The 1990 problem on page 7 - notes on page 4 could be helpful
The challenge problem is on page 9! Have fun!
Periods 3-4:
Take a look at the problems for yesterday, and see if there is any consensus. Ampere's law depends on the current inside the region you are looking at, analogous to Gauss's law depending on teh charge inside the region.
One application of Ampere's law for straight wires, where B = (mu)I/(2*pi*r), is to get the force between two currents. Check out a video on the forces between two long wires with currents - they are both producing magnetism, so the wires should either attract or repel each other! Take good notes, this will be needed for some of the homework. Note that the force on currents is F = IL x B, where L is the length of a segment of the wire.
Then, take a look at a video on the initial exposure to Biot-Savart law. This is the rule that allows us to determine the magnetic field for things more exactly (Ampere is only for long wires, solenoids, and toroids, so it is limited). We will look at what a single moving particle does in terms of producing a magnetic field. Take good notes, because we will build on this.
Try the following from the packet:
Ch. 28 #8 (B-S law), 31 on page 7
AP Prob from 1983, page 11
Periods 1-2, 8-9:
Yesterday you saw something on Faraday's law for a moving hoop/changing area example. This is the case where induced voltage = B dA/dt. Today extend on this by looking at cases where a second force is trying to push a circuit through magnetism, such as dropping a metal hoop into a B-field. What you will see is that, because this process depends on speed, it ends up looking a lot like air friction and terminal velocity from last year! Weird, but true. Remember the case of you trying to swing the metal hoop through the big magnet, and you felt the forces on it trying to slow it down (this is a magnetic brake). Take good notes so you can try to make sense together of the home work problems - see if you can complete things before leaving.
Homework set:
The glider problem on page 6 is based on yesterday - use the notes on page 2 and 3, could be helpful
The 1990 problem on page 7 - notes on page 4 could be helpful
The challenge problem is on page 9! Have fun!
Periods 3-4:
Take a look at the problems for yesterday, and see if there is any consensus. Ampere's law depends on the current inside the region you are looking at, analogous to Gauss's law depending on teh charge inside the region.
One application of Ampere's law for straight wires, where B = (mu)I/(2*pi*r), is to get the force between two currents. Check out a video on the forces between two long wires with currents - they are both producing magnetism, so the wires should either attract or repel each other! Take good notes, this will be needed for some of the homework. Note that the force on currents is F = IL x B, where L is the length of a segment of the wire.
Then, take a look at a video on the initial exposure to Biot-Savart law. This is the rule that allows us to determine the magnetic field for things more exactly (Ampere is only for long wires, solenoids, and toroids, so it is limited). We will look at what a single moving particle does in terms of producing a magnetic field. Take good notes, because we will build on this.
Try the following from the packet:
Ch. 28 #8 (B-S law), 31 on page 7
AP Prob from 1983, page 11
Thursday, March 17, 2016
Classes for March 17
Periods 1-2 and 8-9:
We will dive into the electromagnetic induction material! Check out two videos, for the case where we have a constant magnetic field and a moving chunk of metal or circuit. This is the case of
emf = induced voltage = -B dA/dt. The first is about just moving a piece of metal through a magnetic field. The second is about moving a circuit into or out of a B-field, where the area is changing. Take good notes, and you can try AP problems from 1981 and 1984 (pages 5 and 8 in the packet).
Also, start doing an error analysis on the last magnetism quizzam (solutions have been on the web site).
Periods 3-4:
3rd period you will need to do the school survey. After this, check with each other about answers to last night's set. Once done, then watch a video and take notes on Ampere's law - this is similar to Gauss's law for electric fields, only for magnetism!
Try the AP problems on pages 8 and 9 in the packet from yesterday.
We will dive into the electromagnetic induction material! Check out two videos, for the case where we have a constant magnetic field and a moving chunk of metal or circuit. This is the case of
emf = induced voltage = -B dA/dt. The first is about just moving a piece of metal through a magnetic field. The second is about moving a circuit into or out of a B-field, where the area is changing. Take good notes, and you can try AP problems from 1981 and 1984 (pages 5 and 8 in the packet).
Also, start doing an error analysis on the last magnetism quizzam (solutions have been on the web site).
Periods 3-4:
3rd period you will need to do the school survey. After this, check with each other about answers to last night's set. Once done, then watch a video and take notes on Ampere's law - this is similar to Gauss's law for electric fields, only for magnetism!
Try the AP problems on pages 8 and 9 in the packet from yesterday.
Monday, March 7, 2016
Some links for classes the week of March 8-11
While Doc V is out of town, here are some links:
Periods 1-2, 6-7, 8-9:
On Tuesday, after reaching consensus on the homework problems, check out a video on rolling without slipping. This is the type of motion we would expect to have for things that roll. When there is NO SLIPPING, this means we have no heat being generated, and we can use the relationships s = R*(theta), v = Rw, a = R*(alpha). Take good notes, and feel free to replay any parts that are confusing. Also, on the blog is a video on the equilibrium stuff we did last week (balancing torques), in case anyone wants to see another example of left = right, up = down, and cw = ccw.
After watching the video, see if you can make it through the 1997 problem on page 18 of our packet; work in small groups to see if the video made any sense. Then you can try some of the homework problems before leaving: Page 13 of packet, Ch. 9 #83 or 84 (choose one); and page 14 of packet, the AP Problem from 2002. These all make use of energy! Remember, the only new thing is adding in (1/2)Iw^2 for rotational motion.
On Wednesday and Thursday, Adam is in!! For links to the lesson, go to Adam's web page. Have phun!
On Friday, someone can pull up the solutions to the 2002 problem from Tuesday and see how it went together. Then check out a video on something tipping over, with NON-constant angular acceleration. Take notes on this. You will then have time to try a problem from 1999, on page 15, which builds off the video. Also, you can take a look at the problem on page 19, from 1994, making use of a few ideas from energy.
Periods 3-4:
On Tuesday, before going back to the lab, check out a video on charged particles moving through magnetic fields (B-field). Take good notes, we will be using those later. Then get back into the lab and try to complete it before leaving. You will need the data from the graph portion for when Adam is here Wednesday and Thursday.
For homework, try to make sense of the Band Theory Review on page 3 of our packet. This gets into the difference between conductors, insulators, and semiconductors from a quantum point of view. Check out the video on this band gap theory as a guide, and try to summarize it on page 3.
On Wednesday and Thursday, Adam is in!! For links to the lesson, go to Adam's web page. Have phun!
On Friday, watch the Nova video called "Magnetic Storm," and answer the questions on page 10 of the packet. These will be collected next week. If there is time, there is also a video on mass spectrometers which you should watch in class (or at home if not enough time), in order to do the homework problem on page 13 (from 1984).
Thank you all for your cooperation this week, and for all the support! I am really proud of and thankful for each of you! I cannot wait to come back and have some discussions about all we are working on out in Dubai.
Periods 1-2, 6-7, 8-9:
On Tuesday, after reaching consensus on the homework problems, check out a video on rolling without slipping. This is the type of motion we would expect to have for things that roll. When there is NO SLIPPING, this means we have no heat being generated, and we can use the relationships s = R*(theta), v = Rw, a = R*(alpha). Take good notes, and feel free to replay any parts that are confusing. Also, on the blog is a video on the equilibrium stuff we did last week (balancing torques), in case anyone wants to see another example of left = right, up = down, and cw = ccw.
After watching the video, see if you can make it through the 1997 problem on page 18 of our packet; work in small groups to see if the video made any sense. Then you can try some of the homework problems before leaving: Page 13 of packet, Ch. 9 #83 or 84 (choose one); and page 14 of packet, the AP Problem from 2002. These all make use of energy! Remember, the only new thing is adding in (1/2)Iw^2 for rotational motion.
On Wednesday and Thursday, Adam is in!! For links to the lesson, go to Adam's web page. Have phun!
Periods 3-4:
On Tuesday, before going back to the lab, check out a video on charged particles moving through magnetic fields (B-field). Take good notes, we will be using those later. Then get back into the lab and try to complete it before leaving. You will need the data from the graph portion for when Adam is here Wednesday and Thursday.
For homework, try to make sense of the Band Theory Review on page 3 of our packet. This gets into the difference between conductors, insulators, and semiconductors from a quantum point of view. Check out the video on this band gap theory as a guide, and try to summarize it on page 3.
On Wednesday and Thursday, Adam is in!! For links to the lesson, go to Adam's web page. Have phun!
On Friday, watch the Nova video called "Magnetic Storm," and answer the questions on page 10 of the packet. These will be collected next week. If there is time, there is also a video on mass spectrometers which you should watch in class (or at home if not enough time), in order to do the homework problem on page 13 (from 1984).
Thank you all for your cooperation this week, and for all the support! I am really proud of and thankful for each of you! I cannot wait to come back and have some discussions about all we are working on out in Dubai.
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 http://media.pearsoncmg.com/aw/aw_activphysics/activphys.html. 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...
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 http://media.pearsoncmg.com/aw/aw_activphysics/activphys.html. 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.
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.
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.
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