# DR. SHIELDS' CLASS

our class blog

## Physics on 4/18/13By honorsphysics12o, April 18, 2013

By honorsphysics12o, April 18, 2013 | | Honors Physics (1-2 O)

Shields started the day with a warm up involving the distance of the planets from the sun against their velocity. After we had all plotted the data, and then tried to put an equation to the data, Shields explained to us the true type of equation of the data—a power function. A power equation is an equation whose form is V=D1/2. As we learned back in the gravity unit, mv2/r=GMm/r2, which can be reduced to V=G (1/√r), this is good because they are orbiting a center of gravity. And so we have used data to plot a behavior that follows a function. For our group, the power curve fits the data with an r2 value of .9998 (For those of you who haven’t taken stats, the closer to 1, the better the function fits the curve, in this case, it fits very well).

Shields then instructed us to go to a link on his website to get data on the Milky Way. After we had plotted the data, it was obvious that the actual data does not fit the actual curve. As a special bonus, Shields had us plot what theory would predict, and that is a drastically different plot. Finally, after we had finished that, he had a second special bonus, which was to do the same as above, only for the Andromeda Galaxy (NGC 224).

After we had finished this, Shields then put on a movie about gravity, dark matter, and why everything is not following the patterns we thought it would, the same videos we have been working through over the past few days. We started with Professor Frenk, a man whose job description was to figure out the universe. This man and his colleagues through their research looked at the amount of the amount of matter and dark matter of the universe, they found even less dark matter than they thought, and they were puzzled, and a hole appeared. Then they found out that the universe was not expanding slowly as they thought, but actually quite quickly. And, because of the energy required, they believed that they thought that they found what could fill the gap, and what was needed for the big bang theories—dark energy. They believed that they found cosmology’s standard model, 4% matter, 21% dark matter, and 75% dark energy. Then the movie consulted a skeptic, who doesn’t believe the standard model. The professor they consulted earlier used the proposals and used that to create a computer simulation of the universe. This simulated universe was virtually indistinguishable from the real universe, and gave Prof. Frenk what he thought he needed.

There is nothing due next class.

By Richard and Wade

## ROTATION CURVES OF SPIRAL GALAXIESBy Dr. Shields,

By Dr. Shields, April 18, 2013 | |

## Random information by Cee-CeeBy honorsphysics12o, April 14, 2013

By honorsphysics12o, April 14, 2013 | | Honors Physics (1-2 O)

Hey guys, I found these videos on youtube that explains/ updates the world abou the Higgs Boson particle. Both start off pretty boring, but after the first few minutes it actually becomes interesting and useful, especially if you want to be a scientist.

To keep to the random information title, I found a bunch of facts about Cern:

 LHC Machine Outreach Interesting facts
 Home Introduction Pictures Favourites Photo Gallery FAQ

## Physics on 4/12/13By honorsphysics12o,

By honorsphysics12o, April 14, 2013 | | Honors Physics (1-2 O)

Mia and Vail

Today, we came in from the rain and cheered up with an exciting and stimulating warm-up problem, which helped us review for our circuit quiz next class. The questions were: 1) Find th equivalent resistance of te entire circuit (16.3 ohms)  and 2) What is the current which runs through the ampmeter?(0.29 mAmps)

We also brushed up on our physics/english vocabulary, which will make circuits easier. Remember, Voltage = across a circuit, Current = through, and Resistance = of an object. Dr. shields then went over the trickier last problems on our homework, which, by the way, is due today, except for the last problem. We did an assesment (not for a grade) so that we can retake it again at the end of the school year, which is in 7 weeks, and show the mountains of knowledgewe crossed in that time. Not too bad, the only confusing part was the numbering of the questions.

Then we watched a physics film! It was about atoms, the universe, british people, the usual. We only got through a part of it, so we will finish it later.

(“The Big Ear” of Puerto Rico)

And that’s that. Happy Friday!

## Physics on April 8th,2013By honorsphysics12o, April 13, 2013

By honorsphysics12o, April 13, 2013 | | Honors Physics (1-2 O)

Hope everyone have nice spring break!!

Hello Guys, this was the class on April 8th.We started class by talking about field trips to CERN and Ireland during spring break.We reviewed about CERN and the different particle accelerators.We get chance to know some amazing facts about CERN.While digging a shaft for the LHC, the workers run into an underground river.

They poured an some amount of nitrogen that freeze the whole river then digged through the ice. Then the poured cement into the ice to build a tunnel.We discussed about CMS.It is a huge coil of wire that has 19000 Amps. The CMS detector at the CERN has the strongest B field on the plant at 4 Teslas. Dr.Shields explained about electricity and power lines.

We know that there are two distinct kinds of power lines: the wooden and metallic.Electricity is made at the power plant, and they send it out at a couple hundred thousand volts through the bigger metallic power line. Dr.Shields told us to go around CHS and find the main power line from where school received electricity from.

He gives us some hints about distinction between the Great White Electric Poles and the Lesser Wooden Poles. Each have insulators attached to them to separate the metal from the high voltage.The insulators are about 9 feet long which have horizontal cylinders.

After that we went around our school searching for our answer.While searching for our answer we saw transformer which converted the high voltage into lower voltage and many others things like main AC and other sub power lines which were used for school purposes.

Finally,we were back to our class with our answer. At last, we watched some videos which are based on Physics topics until the class was over.

## Quiz on Tuesday/WednesdayBy Dr. Shields, April 12, 2013

By Dr. Shields, April 12, 2013 | |

Here is your review.  Check out the circuit below.

1. What is the equivalent resistance of the circuit?
2. How much current goes through the ammeter, AM2?

Scroll down for the answer.  If you are correct, you are ready for the quiz!

1. R2 is in parallel with the parallel combination of R3 and R4, which is in parallel with the series combination of R5 and R6.  That gives you a resistance of 6.3 Ω.  Add that to R1 and the equivalent resistance of the circuit is 16.3Ω.
2. Well, the current leaving the battery is I=V/R = 10/16.3 = 0.61 A.  So, the voltage dropped across R1 is V = IR = (0.61)(10) = 6.1 V.  So, there is 3.9 V left across the three parallel branches.  So, the current through the ammeter is I = V/R = 3.9/13.3 = 0.29 A.
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## Physics 4/10/13By honorsphysics12o, April 10, 2013

By honorsphysics12o, April 10, 2013 | | Honors Physics (1-2 O)

April 10, 2013

Hello chiquititas and o’s I suppose, it is Devan and Hollis once again.

We started class today with a bang! We watched a video made by those brilliant kids at CERN about the biggest bang of them all, the big bang. Hubble predicted that because the universe is expanding, it must have started with an iniinitely small explosion.  To recreate this explosion and understand the beginning of the universe, particle accelerater smash subatomic particles together in controlled situations

We’ve been learning about magnets and electricity lately and should remember that the two are closely linked, and in fact, two sides of the same coin. Maxwell came up with some important equations that help us understand this relationship:

F=(qv)x(B) Force equals charge times velocity times the magnetic field. However, these are vectors, so working the equation is not as simple as we’re used to.  When you find the crossproduct of two vectors, the resultant is perpendicular to both.  To find the direction of cross product, you can wrap your fingers in the direction of the fields, and your thumb will point in the direction of the corssproduct.

If two vectors are perpendicular, the cross product is maximizes.  Because of this you can rewrite the equation with sin, because it is maximized at 90 degrees, but minimized at zero.

F=qvBsinø.  This equation tells you the magnitude but nothing about direction.

Fun fact: the CMS detector at the CERN has the strongest B field on the plant at 4Teslas

The answer after you plug and chug is 64 pN even though this seems kind of small, electrons are really small too so this little electron is going to bend a lot!  However, rarely is there only one single particle, because in a wire, there are billions and billions of electrons and their force can add up.

Then we tried to make a real life application of this.  We took  battery with a magnet on the bottom with a stripped copper wire on it. As depicted behind Dr. Shields in the photo to the left, or for a clearer image below.

WE HAVE A QUIZ TUESDAY ON OHM AND WHAT NOT!

The homework will be due Friday minus one problem.

We reviewed for the rest of class:

Voltage, resistance, and current

## Class on Thursday, March 28, 2013By honorsphysics12o, March 28, 2013

By honorsphysics12o, March 28, 2013 | | Honors Physics (1-2 O)

Hello class! Happy Almost Spring Break, I hope you have tons of exciting plans.

Today in class, we talked more about circuits and dove more into the properties of electricity and magnetism. For the majority of class, we learned about how these two charges are related. Dr. Shields made an excellent comment about the history of Physics which I think encompasses today’s lesson perfectly. He said that the point of all the experiments and discovery is not to find more weird and unexplainable things and properties; it is trying to make connections and trying to understand things in the easiest way possible.

We started off the class with a warm-up similar to the ones we have done before of creating a circuit.

Then, we added a compass to the mix. We placed the compass on the table and found North. Then, we aligned the needle with one of the wires in our circuit. If observed closely, we found that when aligned with the wire, the needle deflected slightly West. WOW! Why does it do that? Well, Dr. Shields ruined the mystery by explaining that the needle deflects West because the direction of the current through the circuit is moving in a circular motion to the left. You see, every second, 1×1018 electrons are moving through the circuit because of the electricity being passed through it, exciting the electrons. Because of these moving electrons, another field is produced: a magnetic field. The point and root of the warm-up in simple terms is that the moving charges of an electric force cause magnetism. Our planet has magnetic properties because the core of the Earth is composed of metals that are called convection currents. These convection currents that are constantly moving create flowing currents that cause our poles to have magnetic charge.

Michael Faraday was an influential figure in the discoveries of the properties and understanding of the relationship between electric currents andmagnetic fields. His work is a large part of why we understand the scope of the relationship between the two. Modern technology couldn’t exist without the basis understanding of the properties and without understanding that electricity and magnetism are two sides of one coin. The technology that we know today couldn’t exist without just one.

Two most important concepts to take away from today:

1. A moving charge creates a magnetic field
2. Moving charge in a magnetic field feels a force

We have talked about the first some; now let’s touch on the second. When a force in inflicted on a magnet outside the electric current, it must go in the direction of the velocity of the current. As a result, the protons in the material bend to the left.

Next, we talked about permanent magnets next. Permanent magnets are unique from ordinary magnets because they are first magnetized but then produce a constant magnetic field on their own. The field lines in a permanent magnet go North to South. We played around with the properties of Dr. Shield’s permanent magnet by messing with the color of the TV. The TVs at CHS are old and use what is called a cathode ray tube which has a gun in the back that shoots electrons at the screen. Each picture is created by the gun shooting the right number and sequence of electrons at the red, green or blue pixels. By putting the permanent magnet by the television, it pushed the electrons that the cathode ray tube was shooting, thereby changing the color of the screen. This was a super cool demonstration of a wicked property of magnets…until Dr. Shields broke his TV. Way to go!

Next, we talked about how this has to do with our old friend the LHC.

To explain the correlation, Dr. Shields went into great detail about the process that takes place at the LHC. He started by explaining that the material for all the experiments and research and billions of dollars spent is in a can the size of Dr. Shield’s water bottle. This can is filled with enough hydrogen atoms to fuel every experiment they will ever conduct at the LHC. First, they take the proton(s) out of the can and subject it to an electric field which extracts the electrons, leaving you with only protons. With the protons, they then subject them to another electric field that accelerates them into the next stage. Next, all the air is sucked out of the tube, leaving the linear accelerator to move the protons at about 1/3 the speed of light. The protons are then sent into a series of circular accelerators where they then enter the LHC. Contrary to popular misconception, the LHC is not circular; it is a series of many f 50 foot stretches that alternate between being straight and slightly curved. It seems like a circle because it is 17 miles and in comparison, 50 feet is not enough to see a visible difference.  In the straight sections, they apply a strong electric field to the protons, pushing them into higher accelerations. Because it is a vacuum and they don’t want the protons to hit the sides, the next section is intended to bend them. To do this, they put a coil of wire on the sides, causing the protons to bend with the shape of the tube. The next section is intended to squish the protons. They do this by putting magnets on all the sides, repelling it from all surfaces. This is called focusing the protons. The result is squish, bend, accelerate repeated over and over again.

The reason the collisions appear to be like fireworks or showers is because there are 8 HUGE magnets creating magnetic fields that bend the protons in different directions.

All of the work at the LHC can be partially explained by a crazy concept that Einstein introduced us to: making mass out of energy. Einstein gave us E=m. The price you pay is C2 : E=MC2 . However, the LHC utilizes this equation to make mass by using the conversion to M= E/C2 .

If you are still confused, watch this video. It is short but gives a good overview of the basics.

Have a great Spring Break everyone!

Sydney and Edriss

## Tuesday March 26, 2013By honorsphysics12o, March 27, 2013

By honorsphysics12o, March 27, 2013 | | Honors Physics (1-2 O)

I’ve got a 120V voltage source and 5 bulbs, each with the resistance of 500Ω. How much currency will I use if I connect them in series? What about in parallel?

Hey guys, Cee-Cee here, today in class we reviewed the concepts of Ohm’s Law.

We used the following steps to complete the warm up:

•  Found the total resistance (Req) = 500+500+500+500+500=2500Ω
• Found the currency(I) I=V/R= 120/2500= 0.48A=48mA
• Found the resistance in parallel= ((1/500)5)^-1= 100Ω

After the warm up, Dr Shields went on to explain the difference between series and parallel in circuits. He said the current is constant in a series because it is the counting of electrons, if the count of electrons are the same at each point then there is a “leak” . The equation V=I/R shows how much voltage dropped at each resistor.

This is how to visually identify a series.

He went on to describe a circuit in parallel. In a parallel circuit, the currency is not constant because it is measured differently at each point (Itotal=V1/R 1+ V2/R2+….Vn/Rn). However, the circuit is receiving the same amount of voltage.

After that he attempted many times to demonstrate what it means when something short circuits/ how it happens. When something short circuits, it means that the resistance is low and the currency is high, which leads to the production of more heat causing it to blow/stop working. He finally got things to work. We witnessed a wire melt into thin air.

From that, we shifted into a mini lab using batteries, wire, clamps, a ammeter, and color resistors. To determine the actual resistance of the resistors, we used a resistance calculator online. Class ended before he could really explain what we actually did but I think he will review it next class.

That’s all for now! Don’t forget homework is due Wednesday!