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Part
One: Electric
Surprise
 าDing!ำ
You rush to the microwave and open the door. The delicious smell of warm chocolate chip cookies hits you right in the nostrils. Yum! As good as homemade in just 30 seconds. How is that possible?
To find out, take a few steps back in time. Our journey starts in 1820, at the home of a Danish professor.
Hans Christian Oersted had invited several students to observe his experiments with electricity. At one point, Oersted brought a magnetic compass near an electric wire. Suddenly, the compass needle jumped. That was a surprise! Oersted had discovered a connection between electricity and magnetism.
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 Magnets
Compass needles are magnets. All magnets are surrounded by invisible
magnetic fields. Compasses point north because the Earth itself is
a magnet, and the Earth's magnetic field affects compass needles.
But if you place a magnet near the compass needle, the needle lines
up with the invisible field of that magnet.
When Oersted held an electric wire near his compass, he discovered
that an electric current (the movement of electricity through a wire)
makes its own magnetic field. [See "Pushing Science Further"
below.] This is important because it means you don't need a magnet
to create a magnetic field. |
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Pushing
Science Further
Turn Oersted's wire into a coil. In the centre of the coil place a
spring-loaded metal cylinder. You now have a solenoid, a device that
moves whenever the electric current is turned on or off. The solenoid
would become the heart of one of the world's first mass-communication
inventions, the telegraph. |
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 Magnetic
Fields
Now let's jump to 1831, England. Michael Faraday, a scientist with
little formal schooling but great scientific intuition, wondered about
Oersted's discovery. If electric currents made magnetic fields, could
magnetic fields make electric currents?
Yes, but Faraday found that only a changing magnetic field could make an electric current. One way to change a magnetic field was to move a magnet. Faraday had discovered a connection between motion and electricity. This connection led to electric motors and electric generators. Generators turn motion into electric current. Motors work the other way, turning electric current back into motion.
Electric motors and generators powered the Industrial Revolution that
lit up cities and switched on factories. But Faraday's discovery would
lead to much more, as we'll see in part two of our story. |
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The Story
So Far:
Introduction
Part One:
Electric Surprise
Part Two:
Waves Over the Ocean
Part Three:
Death Rays and Bouncy Waves
Part Four:
The Drive to Get Shorter
Part Five:
And Now for the Chocolate
Part Six:
Nuke It
Bonus Feature:
Watch Us Dismantle a Real Microwave Oven
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