Magnets—Mundane and Marvelous

While you type at your computer, they sit right in front of you.  On your way home from work, they come along for the ride as you listen to your car radio, or stream music from your smartphone.  You can't escape them.  They're everywhere.  
But don't panic.  They can't hurt you.  In fact, without them, life in the 21st century would come to a standstill.  So what can they be?  Here's a hint—they possess an attractive personality.

Magnets exist in household appliances, transportation vehicles, security and medical devices.  People use them daily without a second thought, but don't give magnets their due.  They overlook their importance to modern society and don't know how many marvels magnets perform.  Some people even lack a basic understanding of magnets.

Magnetite, also known as lodestone.

(University of Minnesota Dept. of Geology photo)

Heavy metal

So what exactly makes up a magnet. Naturally occurring magnets contain a mineral called magnetite.  Magnetite contains iron oxides, a different form of iron—a magnet's key ingredient.  Magnetite creates its own magnetic field, which either attracts or repels other magnets.  Manufactured magnets contain an alloy, a metal made by combining other metals.  In this case, they contain aluminum, cobalt, nickel and iron.

Refrigerator magnets belong to the manufactured group.  We call these magnet types "permanent" magnets.  We call the not-so permanent or temporary magnets "electromagnets."  These need to use an electrical current from a battery to produce a magnetic field.  This magnetic field only lasts until the power gets cut off.  Depending on the size of metal and battery used for electromagnets, they can lift just about everything metal, from paper clips to steel I-beams. 

Iron filings give a visual representation of a magnetic field.
(Malacara photo)

Magnetism

Magnetism (or electromagnetism) is one of the four fundamental forces in our universe. Simply put, it's a force of attraction (or repulsion) that acts over distance. It does so through a magnetic field, which gets created by movement of electrically charged particles. The earth generates its own magnetic field because as it spins through space, it churns up its molten core, which contains iron. The sun also generates its own, much more powerful magnetic field. 

How does the sun do it? According to the astrophysics department at Cornell University, the center of a star is warmer than its surface. This temperature difference causes the gas to rise and float towards the surface, just like a hot air balloon. At the same time, cooler surface gas sinks. This is called convection. 

Ordinarily, according to the Cornell profs, convection does not produce a current because the matter is neutrally charged; but when the stellar matter is so hot that it becomes a plasma (charged gas that's conductive) the charges are forced in different directions by an initial magnetic field. As the charges move, they generate a magnetic field of their own, which adds to the original field. This produces a feedback effect until the magnetic field becomes self sustaining. This is what's called a dynamo.

An MRI machine lines up the hydrogen atoms in your body
to show doctors internal injuries. (Jan Ainali photo)

They see through people?

One might ask, do magnets only work on metal objects?  Believe it or not, magnets also work, albeit indirectly, on the human body. In 1977, medical researchers developed a machine capable of peering inside the human body without using X-rays. The machine's creators dubbed it MRI, or Magnetic Resonance Imaging. According to radiologist Todd Gould, this device uses powerful magnets to surround a patient in a magnetic field while also beaming radio waves inside living tissue.  The MRI switches on and off rapidly, creating a picture of variations in the alignment of hydrogen protons inside the tissue.  Protons make up a part of atoms,  basic building blocks of all matter in the universe.  Hydrogen atoms only have one proton, making them the perfect candidate for this non-invasive scan.  In short, the damaged tissue reacts differently to the magnetic field and radio waves than normal tissue, thereby showing your doctor exactly where you hurt and speeding up recovery time.

A superconducting magnet, coupled to a nuclear reactor,
could propel a spacecraft to Mars and beyond.
(NASA image)

Magnets as engines

Magnets not only work in inner space, they just might move us around in the near future in outer space.  According to David Goodwin, program manager at the U.S. Department of Energy's Office of High Energy and Nuclear Physics, a superconducting electromagnet vibrating about 400,000 times a second can create enough momentum to move a spacecraft, if coupled to a nuclear reactor, all the way to Mars and beyond.  A superconducting magnet contains a wire made from a special alloy, called niobium-tin, wrapped around a metal cylinder.  The wire lacks resistance to electricity, making it extremely efficient in producing power, because liquid helium cools the superconductor to -452 degrees Fahrenheit to keep it running.  The superconducting magnet then gets coupled to a metal plate, made from copper, iron or aluminum, to help it vibrate faster.  This type of propulsion system, however, remains unproven.

The lowly magnet provides an invaluable service to every aspect of our society. It not only adds comfort to our everyday lives, but also stirs the imagination by aiding our exploration into inner and outer space.  Magnets, however large or small, will help build a better, brighter future.

***

Homemade refrigerator magnets are one way to show
your child how fun science can be. (Malacara photo)

How To Make Magnetic Magic

"Mommy, how does a magnet work?" Your child might unexpectedly throw this question your way one day, perhaps during a long car trip to grandma's house, or when your child tries to "con" his or her way out of cleaning out the refrigerator.  Whenever it happens, you don't want to catch yourself saying, "Hey, I'm not MacGyver; how should I know?" or, "Go ask your father."  If you want to say something smart, then keep reading.  Not only will you learn the right answer, but you will also know how to help your child make a magnet.  With your guidance and a few simple items from your kitchen's junk drawer, your child will possess the power to unlock one of modern science's secrets.

Gather up these few items from around your house:

*  one D-cell battery

*  3-4 feet of wire (16 to 20 gauge)

*  an iron nail

*  electrical tape

*  paper clips

If you lack any of these items, just make a quick trip to the big-box hardware store or home specialty store and buy them.  Once in hand, take the wire and cut off the surrounding plastic coating on the ends to expose the copper underneath.  Wrap the rest of the wire around the nail, leaving a few inches on the ends to connect to the battery.

A very simple, inexpensive-to-make electromagnet.
(Malacara photo)

Connect one end of wire to the battery's positive tip and the other to the negative tip.  Use a piece of electrical tape to make the connection complete.  To test the electromagnet, spread out the paper clips on a table and wave the wire-wrapped nail over them.  If the battery and connections work, the clips should immediately stick to the nail.  If not, recheck the connections or replace the battery.

If you want to really impress your child on your newly acquired science knowledge, try out this variation on the previous project.  This time, lose the nail and find a circular permanent magnet.  Also, find two large paper clips.  

Take your wire and wrap it around the battery.  Leave about 3 inches unwrapped on both ends and remove from the battery.  Wrap each end through the coiled wire about 3 times to secure it.  Straighten out the exposed ends to create an axle.  Take the large paper clips and bend each of the ends to form hooks.  Attach one paper clip end to one end of the battery and do likewise with the other clip on the battery's other side. Take the coiled wire and place it into the hooks not attached to the battery.  Attach the circular magnet to the battery opposite the wire coil.  Now slowly begin to spin the coil, making sure the axle remains straight.  Make adjustments to the coil and magnet accordingly.  The coil should start to spin on its own.  If it does, then congratulations, you just made a simple electric motor.

This electric motor used to change the channel in a very
old television set. (Malacara photo)

This simple project gives your child a very good idea on how magnets and electricity work together.  Now that your child knows this, you can show him or her how much we rely on magnets.  They exist inside headphones, cell phones, DVD or Blu-ray players, and televisions.  They also exist inside our cars, provide electricity to our cities, and might one day propel spaceships.  By uncovering one of nature's fundamental forces, you might give your child the gift of a "permanent attraction" to science and a step into the future.

© 2013 Martin Malacara