
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.
~~~~~~~~
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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