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Krampf #485 Spark Plugs
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KRA-@aol.com
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May 02, 2007 19:59 PDT
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Robert Krampf's Experiment of the Week: #485 Spark Plugs
Greetings from West Palm Beach, Florida. Wow, my summer break is getting so
close I can almost taste it. I love doing shows, but Nancy and I are
planning a trip west, and I can hardly wait to hit the road.
I updated my blog with a trip to the Chihuly Exhibition at Fairchild Gardens,
in Miami. There is also a new science video on my website. This week's
video is how to make a Cartesian Diver.
This week's experiment comes from a very common question that I get about
electricity. Many people notice that you sometimes get a spark of electricity
when you unplug an appliance.
To find out why, you will need:
aluminum foil
A D cell or 9 volt battery
a dark room
WARNING!!! The electricity in the wires of your house has enough amperage to
kill. Never put anything into an electric outlet that was not made to go
there. Doing that could cause fires or serious injury.
Tear a small strip of foil, about an inch wide and about 4 inches long. The
size is not critical. Just be sure that it is long enough to reach from one
end of the battery to the other.
Hold one end of the foil strip against one terminal of the battery, either
the bottom of the D cell or one of the contacts on the 9 volt battery. Holding
the other end of the foil in your fingers, darken the room. The darker the
room is; the better this will work. Wait a few seconds, to let your eyes get
used to the darkness. Then gently brush the free end of the foil against
the other terminal of the battery. For the D cell, you brush it across the
top, and for the 9 volt battery, you brush it across the other contact. What
happens? You get tiny sparks!
Understanding the Science
Why? First, we have to understand what an electric spark really is.
Normally, air is an insulator. It does not easily conduct electricity. If we
push the electricity with enough voltage, we rip some of the electrons away from
their atoms, changing the air from a gas into a plasma. When electricity
changes the air into plasma, we call that a spark. OK, what is a plasma?
Most people learn the three states of matter in elementary school. When
they get to high school, they find out that there are four states: solid,
liquid, gas, and plasma. If they go on to study chemistry in college, they find
out that there are really many more states of matter. The number keeps
changing as we learn more about the universe. For today, the state we are
interested in is plasma.
A plasma is like a gas, but some of its electrons are loose, not bound to the
atoms. Plasmas are good conductors of electricity. They also glow, giving
off light, which is why we see the sparks. The Sun, fluorescent lights,
neon lights, and sparks are common examples of plasma. Stars are made of
plasma, making it is the most abundant state of matter.
Normally, we think of sparks with high voltage, but even the low voltage of a
battery can change air to plasma, giving us a spark. The difference is the
size. Low voltages only push the electricity hard enough to produce a very
small spark. As voltages increase, so does the size of the spark, all the way
up to the tremendous voltages of a lightning bolt.
As you remove an electric plug from the socket, there is a point where the
blade of the plug is just a fraction of an inch from the contact in the socket.
At that point, some of the air is changed into plasma, and if the room is
not too bright, you could see a small spark.
Again, do not try using the foil to produce sparks from an electric outlet!
The electricity in those wires has enough amperage to kill you. It would
also burn the foil and the wires inside the walls of your house. Never put
anything into an electric outlet that was not made to go there. It is dangerous
for you and for your house.
Sometimes, when the appliance you are using contains a transformer, you get
even bigger sparks. Transformers use coils of wire to change the voltage of
the electricity. When transformers are suddenly turned on or off, they can
produce a high voltage spark. This is especially common when connecting or
disconnecting laptop computer cords. Speaking of that, my laptop is running
down, so I had better finish this quickly.
Have a wonder-filled week!
Robert Krampf
Robert Krampf's Science Education Company
www.krampf.com
The Happy Scientist Blog
http://web.mac.com/krampf/iWeb/Site/TheHappyScientist/TheHappyScientist.html
Who is Robert Krampf?
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