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Magnetism in the 21st Century

By Brooke Donnelly and Tanner Nelson

Brooke Donnelly

on 27 April 2010

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Transcript of Magnetism in the 21st Century

Magnetism in the 21st Century By: Brooke Donnelly and Tanner Nelson Astronomy First, a few facts about magnetism:

Natural magnets have North and South Poles

Like poles repel and opposite poles attract

Magnetic field lines flow from North to South

Natural magnets are made from Iron, Nickel, and Cobalt

Like poles repel and different poles attract

Magnetic field lines flow from North to South

Magnetic substances can be induced by magnets to become magnets

Medicine Electronics Navigation Toys An example of magnitism in navigation (transportation) would be Maglevs (Magnetically Levitated Trains) Maglevs are trains that are propelled by a linear induction motor and guided be tracks with magnets. Because the track is made up of magnets, the train floats about 10mm above the track on a magnetic field. The train is then propelled by the guidway itself and not an onbaord engine. One advantage of this type of train is that since there is no actual contact with the ground, there are no moving parts which would wear out and have to be replaced. In theory, a Maglev train and its track would need little to no maintnance at all. Another advantage is that since these trains float there is little friction and less noise compared to a conventional steel railway train. An example of magnitism in medicine is an MRI. An MRI (Magnetic Resonance Imaging) uses a magnetic field ten times as powerful as the earth’s magnetic field to take invasive pictures. The magnetic field forces hydrogen atoms in the body to line up in a particular way. When radio waves are sent toward the lined-up hydrogen atoms, they bounce back, and a computer records the signal. Since the magnet is incredibly strong no metal is allowed whatsoever near these machines. The great thing about MRI's is that there is no recovery time afterwards, unless sedation was necessary. After an MRI scan, you can resume your normal diet, activity, and medications.

Aguilar, David "Biggest Stars Produce Strongest Magnets" Web. 24 Apr. 2010.

Cain, Fraser. "Biggest Stars Make the Biggest Magnets." Web. 24 Apr. 2010.

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"HowStuffWorks "MRI - Medical Dictionary"" Howstuffworks "Health" Web. 24 Apr. 2010.

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An example of magnitism involving electronics would be radio antennas. Lots of electonic devices use antennas but one might not know that antennas use electromagnetic waves. A rotating device in a sending antenna charges the upper and lower parts of an antenna positively and negatively. The charges that are accelerating up and down the antenna then transmit electromagnetic waves. When these waves hit a recieving antenna, the electric charges inside vibrate the same way as the variations of the field.
An example of magnitism in Astronomy are magnetars. Astrophysicist Bryan Gaensler (Harvard-Smithsonian Center for Astrophysics) and colleagues announced that they have linked two of astronomy's extremes, showing that some of the biggest stars in the cosmos become the strongest magnets when they die. A magnetar is an exotic kind of neutron star--a city-sized ball of neutrons created when a massive star's core collapses at the end of its lifetime. One magnetar can possess a magnetic field that is more than one quadrillion times stronger than the earth's magnetic field. They are so strong that if a magnetar were located halfway to the moon, it could wipe the data from every credit card on earth. They are known as the "white tigers" of stellar astrophysics because they are so rare, comprising onlys one percent of known pulsars.

In this image, red shows the neutral hydrogen gas mapped with CSIRO's Australia Telescope Compact Array and Parkes radio telescope, while blue represents Chandra X-ray Observatory data showing the magnetar. The bubble in the hydrogen was cleared out by a superstrong wind from the magnetar's progenitor star.
Credit: ATNF/CXC/B. Gaensler (CfA)

Resources An example of magnistism involving toys is the Magic Doodle. The magnetic pen is simply a piece of plastic with a small magnet in the tip. The field of the magnetic pen is strong enough to penetrate the plastic and pull the particles through the thick liquid. The magnetic eraser consists of a bar magnet in a plastic slider. The front of the display is blank (white), and the back has all the particles. They were pulled to the back by the magnetic eraser. The magnetic eraser aligns the particles to one side. If you move the magnetic pen along the display, the magnet on the pen pulls the tiny particles away from the back side to the front side, forming a line.
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