Magnetic Oppression

IB Physics II Research:

Inquiry: September 2012- January 2013

Ludwig Avendano

Amanda Johnson

Table Of Contents

 Content Introduction Method Results and Calculations Conclusion Bibliography Word Document Return to Research

Background Information:
In the 1600s William Gilbert conducted several experiments that greatly expanded our understanding of magnets2. One of the key discoveries is the potential of magnets to be utilized to create electric fields1. Everything from scrap metal sorters, to the tiny chips inside computers contain and harness the abilities of magnets5. Perhaps the use of magnets most related to our experiment are Maglev3 trains, because they use magnets to levitate the trains. This form of levitation is used because it allows the train to float above the track and experience very little friction. However, due to the weight of the train, the strength of the magnetic field is large. Our experiment will be to determine how the levitation height varies with the weight placed on top.

Statement:

The purpose of this inquiry is to investigate the force distance relationship between rare earth magnets when their poles are in repulsion to one another.

Hypothesis:

If a set of 11 magnets is placed in an apparatus in  a way such as for their poles to be repulsion, then more force (in this experiment force will take the form of weight placed on the top of the array of magnets) will be required in order to bring the magnets into closer proximity with one another because the force required to compress the magnets together is inversely proportional4 to the distance the magnets are compressed as a result of their eddy currents.

Variables

Independent: The weight placed on the top of the apparatus in order to bring the magnets closer together.

Dependent: The distance in millimeters between the top of the bottom magnet and the bottom of the top magnet.

Controlled: Other variables were kept constant during the experiment- such as gravity and the apparatus.

Materials:

·         4  7/16x 48 wood rods

·         3  7 diameter by 1 deep wood cylinders

·         11  1/2 diameter by 3/8 deep cylindrical neodymium rare-earth magnets

·         2  Smencil clear plastic tubes

·         1  Drill

·         1  3/8 Drill bit

·         1  7/16 Drill bit

·         1  Ruler

·         1  Pencil

·         1  Roll of Tape

·         1  Set of Weights

·         1  Tube of Superglue

Procedure:

The first thing we did was to obtain the necessary materials for the experiment. After that, we taped the two Smencil tubes together. We then took the time to place in the tubes the magnets individually, alternating the direction of the poles in such a way that they were all repelling each other.We then measured the center on the three bases and divided two of the wood cylinders into thirds by drawing lines. On the divided cylinders, we measured 2.25 from the center and marked it on each of the pre-drawn lines,  drilled a 7/16 hole 1/2 deep on each mark, and drilled a 3/8 hole, 1/2 deep in the center. On the cylinder intended for the upper base, we finished the 3/8 hole with a 7/16 hole. Then to complete the apparatus, we inserted the 3 wooden rods into the 7/16 holes on the bases, and the smencil tubes with the magnets in the center holes. In order to make the holder for the weight we inserted the remaining wood rod through the hole in the upper base and into the Smencil tube, and on the final base we drilled a 7/16 hole 1/2 deep in the center and inserted the wooden rod, thus completing the device. Then we taped and superglued whatever was loose to make the device sturdy, and left it to dry. After it was ready, we placed weight in increments of 100 grams up to 4 kilograms, on top of the weight holder and measured the distance the device dropped in millimeters as we placed weight on the device and recorded the data.

Diagram:

Data Table: Weight Vs. Distance

 Weight (grams)            **Uncertainties are Negligible ** Distance (millimeters) **Uncertainties are Negligible ** 0 221 100 218 200 215 300 212 400 208 500 204 600 201.5 700 198 800 196 900 192 1000 188 1100 184 1200 180 1300 177 1400 172 1500 170 1600 166 1700 164 1800 161.5 1900 159 2000 157 2100 155 2200 153.5 2300 152 2400 144 2500 143 2600 142 2700 139 2800 137 2900 135 3000 133 3100 132.5 3200 131 3300 129 3400 129 3500 127 3600 126.5 3700 125 3800 124 3900 123.5 4000 123

Graph:

** X and Y error bars are negligible**

Calculations:

There were no calculations necessary for this experiment- just interpretation of results.

Summary of results:

Our results showed that there is an inverse relationship between the amount of weight placed on top of the apparatus, and the distance traveled by rod. This is because at first, there was a large difference in between the distance the apparatus went down, and later the difference was much less. There was however a sudden drop between 2300 and 2400 grams, and this is because of friction inside the tube which is our largest source of error.

Our hypothesis was supported by the data, as the force required to compress the magnets was indeed inversely proportional to the distance the magnets were compressed.

It is our belief that  the data turned out this way because as the poles of each individual magnet came into closer proximity with the repulsed magnetic poles of another magnet the eddy currents were forced to work harder to resist their compression which in turn increased the force required to compress the magnets as the distance between the magnets became smaller.

The main sources of error could be attributed to many different components of our research. However, if any single source of error needed to be pinpointed as the largest source, we would place it on the design of the apparatus- in particular the smencils cases which were used to contain the magnets. Because of the quantity of magnets used required two smencils cases, we were forced to tape them together. At first, this did not present many problems if any; however, as time and trials continued the tubes fell out of alignment with one another creating a small ledge on which the magnets could rest creating an increased amount of friction in the tube. Moreover, we were forced to use the smencils cases because the diameter of the tube was extremely vital to the success of the experiment. This is due to the fact that if the diameter of the tube was even a few millimeters larger than the diameter of the magnets then the force of attraction between the magnets would work together with the force of repulsion between them in order to spin the magnets around into a more desirable manner- namely one without repulsion. The flip side of this is that if the diameter was too small then the magnets would fail to fit inside and if it was just right then the amount of friction would increase significantly. The smencils case was the only container that we could find that met the basic requirements for the purposes of our investigation. While the smencils tube was the best resource we could find, it still was not ideal, even the friction inside of the smencils case was enough to cause error in our inquiry. In addition, it is our theory that as the magnets were compressed the smencils case was forced to expand slightly underneath the pressure, this would mean that in the beginning our results would have had a greater amount of friction as compared to the results near the end of our trials.

In addition, as we had never seen magnets of such strength, we had a difficult time pulling them apart or inserting them into the apparatus without having them simply smack back together again. Due to these collisions, several of the magnets were chipped and one was eventually broken in half. While in the beginning these collisions did not seem to be affecting the magnets in a visible way, the chips soon alerted us that there the collisions were causing problems that were not only visible but could also be internal. After finishing the experiment we did some research and discovered that when magnets are brought together with a strong force, especially with rare earth magnets as strong as those that we were using, the electrons inside can be rearranged which can alter the strength and direction of the magnetic field. This new information coupled with qualitative data that the magnets appeared to lose strength has caused us to draw the conclusion that  the magnetic field was indeed affected as a result of the collisions. However, as this is not something that can be directly measured with the equipment we had at our disposal, we are still attributing the main source of error to the problems arising with the smencils case.

While human error plays a role in most experiments, and we are not above that, in comparison with the other sources of error this would have been small. The form in which this would have taken place was in reading the distance. However, because distance was measured in millimeters, this error is negligible. Moreover, there may have been some error in placing the weight onto the apparatus, but again, this would have been minimal.

One improvement to our procedure could have been to readjust the magnets within the tube after each increment of 100 grams was added to the weight holder. This adjustment would have possibly allowed friction to have less of an impact on the accuracy of the data.

With a higher budget and more tools at our disposal, there are several steps we could think of that would improve our design and offer a greater range of data. First, We would want to test several types and grades of magnets, rather than just one set of identical magnets. This would provide a much greater array of data and would offer more information to challenge or support our hypothesis. Secondly, we would look to improve the design of our apparatus. The largest problem presented to us was the friction of the smencils case that held the magnets. With a larger budget and more resources we would seek to minimize this source of error. One idea that would be worth pursuing under no strain of a budget would be to coat a plastic tube similar to the smencils case in size and thickness with a very weak diamagnetic material. This would theoretically produce a magnetic field around the magnets that would limit the friction of the sides of the tubes while keeping a constant under which results could be stabilized. Thirdly, it would be interesting to compare magnets such as the ones at the end of our experiment with new magnets of the same type that had not undergone the same conditions to see if there would be a difference in their strengths. The purpose of this improvement would be to confirm whether or not the magnetic fields are indeed tampered with by the magnets coming together with a pull force such as the one we were testing, and if the electrons were indeed rearranged as a result of our actions.

[1]

"1 The Physics of Magnetism." 1 The Physics of Magnetism. N.p., n.d. Web. 02 Nov. 2012. <http://magician.ucsd.edu/essentials/WebBookch1.html>.

Basic information on the physics of Magnetic repulsion

[2]

"Background Information for Magnets." Background Information for Magnets. N.p., n.d. Web. 02 Nov. 2012. <http://www.sciencetech.technomuses.ca/english/schoolzone/Information_Magnetic.cfm>.

Information on the background and history of magnets

[3]

"Magnetic Levitation." Wikipedia. Wikimedia Foundation, 19 Oct. 2012. Web. 02 Nov. 2012. <http://en.wikipedia.org/wiki/Magnetic_levitation>.

Link about uses and methods for magnetic levitation.

[4]

"Magnetism (physics)." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 02 Nov. 2012. <http://www.britannica.com/EBchecked/topic/357334/magnetism>.

Basic information on the physics of Magnets

[5]

"A Review of Magnets and Magnetism." A Review of Magnets and Magnetism. N.p., n.d. Web. 2

Nov. 2012.

Basic information on the physics of Magnetic repulsion