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Electricity
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Introduction:
Electricity is energy. It flows along wires just as water flows
through pipes. The power behind electricity is from tiny particles
called electrons. Electrons are negatively charged particles that
orbit around the positively charged nucleus in an atom. Inside
the nucleus are both positively charged particles called protons
and neutral particles called neutrons.
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A neutral molecule has an equal number
of electrons and protons. However, as in the case of static electricity,
electrons can move from one atom to another causing one to become
negatively charged and the other to become positively charged.
An atom that has more protons than electrons is positively charged.
An atom that has more electrons than protons is negatively charged.
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An atom that has an equal number of protons and electrons is neutral
and holds no electrical charge. Electricity occurs as electrons
get pushed from atom to atom. It all works because opposites attract!
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Electricity: Teacher Notes
Download:(Abobe Acrobat Reader required--download
free reader)
Supplies needed:
1 Gear Box Circuit Kit (use with a partner)
1 Student Lab Book
1 Static tube
Pencil
Demonstration -- Static Electricity
A simple and safe form of el`ectricity to experiment with is static
electricity. Static simply means not moving. It is the type of electricity
that causes you to get a small shock sometimes when you walk across
a carpeted floor and then touch someone else or a metal object.
It is also the cause of the great hairstyles you can get by rubbing
a balloon against your hair. Your teacher will do some demonstrations
that show the basic principles of static electricity.
You can produce static electrical charge by rubbing certain items.
Combs and balloons become negatively charged when you rub them with
wool or hair. This means that there are more negatively charged
electrons on the comb or balloon than there are positively charged
protons. When you bring the charged balloon up to objects that are
positively charged (such as the hair that you just rubbed), the
two objects will be attracted.
Static electricity will not last for long. Eventually the extra
electrons leak out into the air and the object becomes neutral.
In order to be useful we need electricity that runs continuously
instead of staying in one place.
C. Lab Experiments
Now is the time for you to try building some simple circuits using
batteries. A battery is just a positively charged material separated
from a negatively charged material by a conductive paste. If you
connect these two materials by a wire, electricity flows. In the
AA battery, the negatively and positively charged materials are
at opposite ends of the battery.
The first lab exercise will be to build a simple circuit. Scientists
know that if they use a wire to connect the two ends of a battery,
an electrical current will flow from the negative end to the positive
end. If a bulb is placed in the middle of the wire, it will light
up. Try this by using the equipment in the circuit kits to build
a simple circuit that lights up a light bulb. Follow the other
labs in the lab book to discover the answers to the following
questions.
- What happens if you put two lights in the circuit?
- Try adding a switch to the circuit. What happens if you add
a second switch?
- Try building the series and parallel circuits. In which one
does the bulb burn brighter?
- What happens if you use 2 batteries instead of one?
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