Electricity in Nature
Electricity is not only found
in power lines and electronics made by man, but is also found in nature. In
fact electricity is all around us. We see it in lightning storms, animals use
it as a defense, even our bodies use it to send messages to our muscles.
Lightning
One of the most fantastic displays of electricity in nature is lightning.
Lightning occurs when large amounts of electrostatic energy builds up
in clouds from
the energy of storms. When
electrically charged regions of clouds discharge their energy, a large flash
of electricity can be seen in the sky. Lightning may occur from cloud to
cloud or it can occur from cloud to the ground. Lightning strikes carry huge amounts of energy. A typical lightning strike carries an electric current of
over 30,000 amps and delivers 500 megajoules of energy.
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Lightning also creates a loud noise called
thunder. This is because the air within lightning gets so hot, that it
transforms into plasma for a short period of time. When the molecules of air
turn from gas to plasma, their expansion causes a shockwave that we hear as
thunder.
Animals
Some animals use electricity to survive in
nature. Many of these animals are found in the ocean where some use electricity
to detect objects around them (sort of like seeing) and others use electricity
to fend off predators or even hunt for food.
One of the most famous of the electric animals
is the electric eel. The electric eel can produce large amounts of electricity,
enough to even kill a human or stun a large horse. The eels typically swim into
a school of fish, discharge a large amount of electricity, and then dinner is
served!
Another example of animals using electricity is
electroreception. Many fish such as sharks, lampreys, and catfishes have the
ability to generate electric fields and then use these fields to detect objects
around them. This helps them to "see" in dark areas and to sense
hidden prey.
Human Body
Not only can we see electricity at work in
nature, we are constantly using electricity in our bodies. Every time we move a
muscle, it's the result of an electrical signal being sent from our brain to
our muscles telling them to move. We actually have a complex system of nerves
throughout our bodies that use electric signals to control everything we do.
Static Electricity
Lightning isn't the only form of electrostatic
energy we see in nature. Static electricity charges build up all around us. You
probably have noticed static electricity when you went down a slide at the park
and your hair stood up strait. The friction from the slide on your body caused
a build up of charge that made your hair stand up. Sometimes you can even build
up a charge on your body that will shock someone else when you touch them. This
is static electricity.
The Earth
Deep inside the Earth huge electric currents are
generated from the spin of
the Earth's iron core. These electric currents in turn cause a
magnetic field that extends well beyond the surface
of the Earth and into outer space.
The Earth's magnetic field is important because
it protects the Earth from the solar wind of the Sun. Without the protection of
magnetic field, there would likely be no life on Earth. The magnetic field also
enables the use of compasses to tell the direction.
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