Magnetism
Magnets have fascinated me since I was a child, and I expect many of us can say the same thing. I, however cannot tell you much more than you probably already know about the common magnet. They are fun to play with and I have a few around my place. You know of their north and south poles and how they react to each other.
Magnetism goes along hand in hand with electromagnetic. I will get into that a bit in the next topic page on Electricity. In the subject of electromagnetism I have been, pretty well dipped, having a background in electrical, and electronics.
Historically there were magnetic Lodestones. This makes the magnet real. Also, with what we know today... magnetism is an important part of our Universe, as well as for technology. For the theory of electromagnetism; in 1831, Faraday's experiment of Inducing Current into a wire loop with some of it coiled, by only moving a magnet close to it__ pretty well started it all off. From there, it was also found that by moving a wire loop through a stationary magnetic field, also induces current into the loop. Thus, we now have electro-magnetism.
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We use the principle of the electro-magnet in things like solenoid valves and audio sound speakers. When a solenoid valve is energized there is a coil of wire that makes a magnetic field that draws a metal core up into the coil actuating the valve. Solenoid valves are use by millions, in industry. In our lives you will find them inside clothes washing machines, and refrigerator drinking water systems, for example. This same type of action happens in an audio loudspeaker. A varying current, alternating at an audio frequency, of electricity is passed through a coil that moves the plunger which also has attached a circular movable diaphragm. This diaphragm pulsates the air to give us sound waves. In reverse, a diaphragm spoken into, is hooked to a magnet that can move back and forth through a coil of wire, and will induce audio varying current in the wire. This last sentence describes early types of microphones. (There are also other types of microphones.) However, just about all speakers still use the principle stated. This means speakers in your radios, televisions, hearing aids, stereos, music amplifiers, computers, phones, headsets, and movie sound speakers would almost disappear if you took away electromagnetism. Give a thought to what life for us, without speakers, would be like!
Most all credit cards with the strip on the back are magnetic. Now, many motels and hotels use magnetic swipe cards for door keys. Company and governments use swipe ID cards for authorized entry clearance identification. Now we have magnetic Passport swipe cards.
Lastly here I need to mention that motors and generators have what is called a stator. These stators are the stationary electromagnetic windings inside, and sometimes actually physical permanent magnets mounted to the motor housings. Think about how many electric motors we have and use. Most every vehicle has an electric starter motor. We gave up the hand crank cars quite awhile ago. Tape decks & cassette drives, and CD & DVD drives, without motors would be a problem. Drills, lathes, routers, rotary saws, conveyor belts, blowers, compressors, elevators, are just a few items using mostly electric motors... and just imagine how how many more are out there. They require magnetism to run!
And, permanent magnets are for holding cupboard doors closed. Magnets are used to actuate switches. There are plastic/magnetized flexible signs and cards that can be put on vehicle doors, or refrigerator doors. There is an abundance of toys that use magnets.
If magnetism isn't real, and was taken away from us... it would be a disaster! At least for modern mankind.
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Page Relevant Quotes
""The idea that bodies of matter can "attract" one another is, according to Einstein, an allusion that has grown out of erroneous mechanical concepts of nature. ...Today scientists no longer say a magnet "attracts" a piece of iron by some kind of mysterious but instantaneous action-at-a-distance. They say rather that the magnet creates a certain physical condition in the space around it, which they term a magnetic field; and that this magnetic field then acts upon the iron and makes it behave in a certain predictable fashion."" The Universe and Dr. Einstein, by Lincoln Barnett
