What Is A Magnet

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Magnets: The Natural Navigation Tool Introduction The first mention of magnets in historical reference between 1155 and 1160 where it was written that the city of Carthage was studded with magnets so that an armed man, approaching too closely would be pulled to the wall and held tightly. The next time magnets are mentioned in writing was in 1231-6 by the Bishop of Paris. He explained the motion of the celestial spheres by analogy to the ability of a magnet to magnetize a piece of iron. The compass was known in Europe in the late 12th century so that it is certain that the properties of magnets were known to some Western Europe by that time. What these people would have realized was that the Earth is a large magnet that draws other magnets to it. Since then people have used the magnetic properties to determine north and south.

What is a magnet? A magnet is a force of nature.

Magnets can push and pull. But magnets can only push and pull things that are made of iron, steel, nickel, or cobalt. Magnets are made of iron ore. Magnets have an invisible area around them called a "magnetic field". Magnets push and pull on things that enter the magnetic field. When something is placed outside the magnetic field it looks like the magnet is not working. Magnets can also be so strong that they pass though air, water, and some solid things. The first known magnetic material is a naturally occurring mineral deposit called lodestone. Matter is made up of electrons, neutrons and protons. Electrons have a negative electric charge while protons have a positive electric charge and neutrons have no electric charge. These are the building blocks of atoms. An atom can have a positive charge when it loses one of its electrons, or a negative electric charge when it gains an extra electron.

How does a magnet work? Magnetic fields are generated by moving electric charges. Magnetic fields have magnetic filed lines called lines of force. Magnetic field lines define the direction and strength of the magnetic field. Magnetic fields are the results of magnetic dipoles. An example of a magnetic dipole is the bar magnet. The picture below shows a bar magnet. The magnetic field lines always begin on the north poles of a magnet, and end on the South Pole. Magnetic dipoles always like to align themselves parallel to an external magnetic field so the dipole field matches the one applied to it. This is why bar magnets line up north to south. It also explains the behavior of a compass needle which being made of iron behaves like a magnetic dipole. Dipole means two poles. The direction of magnetic field for the electron and the entire atom moves the magnetic field either North and South.

To identify the north pole of a magnet you can make a compass out of it. The pole that faces geographic north is the North Pole. Like poles repel each other and opposite poles attract each other. So a magnet can repel other magnets. The magnetic forces of a compass will seek north. This means that no matter where you stand on earth you can hold a compass in your hand and it will point toward the north pole. A magnetic compass consists of a small lightweight magnet balanced on a pivot point. The magnet is generally called a needle. One end of the needle is marked "N" for North.

If you don't have a compass, you can create your own in the same way that people did hundreds of years ago. The first step is to turn the item you are using into a magnet. You do this by stroking the magnet along the needle 10 or 20 times. Place your new magnet on a float and it will slowly point toward North.

Maps and Map Reading The compass is used with a map for navigational purposes. A good map will indicate in detail the landmarks, streams, lakes, marshes and mountains, as well as the direction of true north and magnetic north.

To lay out a course on your map, spread it flat so that the north and south lines upon it will be exactly parallel with the north and south line of the compass needle. You can then note in what direction your trail or objective lies and set your course accordingly.

Nature's Compasses There are many compasses that can be found in our surroundings. For example if you have no compass but have a watch, you can tell direction by holding it flat and pointing the hour hand toward the sun. South will be located halfway between the hour hand and 12 on the dial. You could also use the direction by Stars method that was used long ago by seaman and even by the three wise men in the story of Christ's birth. The most easily recognized star group is the Big Dipper or Great Bear, located in the northern sky. This great sky dipper revolves around a smaller group of starts known as the little Bear. The 2 stars forming the edge of the dipper always point to the North Star, a bright star in the very tip of the Little Bear's tail. These 2 stars are called "pointers" and were used in navigation centuries before the compass was invented.

Other natural compasses include the evergreen compass. The feathery tips of pines and hemlocks usually point in an easterly direction. The Rosin weed is another of the wild compass plants that once grew in the Mississippi Valley from Minnesota to Texas. A fall plant of the open prairie its' stiff leaves stand vertically; the leaves pointing north and south. Tree rings will also show a greater growth of wood on the north and northeast sides of the trees.

Man-Made Compasses There are two types of manufactured compasses, the needle and the floating dial. On one a needle rotates and on the other a dial rotates. Both needle and dial are magnetized at one point and swing freely on a pivot pointing north when they come to rest. The rotating dial compass is the best kind for wilderness traveling. A simple compass can be made by rubbing a sewing needle with a magnet and then placing it gently in a cup of water where it will float an point north. To test the usefulness of man-made compasses I used three different items of varying lengths: a darning needle, a knitting needle and a paper clip. After rubbing each one for 20 strokes with a magnet I noted how much change in the compass was made when the item was placed near the compass.

Conclusion After using several items in the above manner I found that the larger the item used to create the compass, the larger the magnetic force it created. I concluded that when making a man-made compass it was best to use a larger item to get the most accurate reading. So the knitting needle was the best item to use.

Bibliography http://www.helterpub.com/_shelter/lost.html http://www.vvs-disposal.com/module/4-5/compass.html http://www.kapili.com/m/magnet.html http://scholar.chem.nyu.edu/~tekpages/magnets.html http://pbskids.org/jayjay/care.curr.cl.17.html http://www.magnequench.com/tech_resources/education/magnets_at_work.html http://www.wondermagnet.com/dev/magfaq.html