Download Electricity - NorthMacAgScience

BASIC
ELECTRICITY
Interest Approach
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Have students make a list of their 10
favorite things to do. After they are
finished with their list, have them circle
the things that involve electricity. Remind
them that batteries are also a source of
electrical energy. This will get students
thinking about the role electricity plays in
their everyday lives and how important it
is to them.
Student Learning Objectives: Instruction in this lesson
should result in students achieving the following
objectives:
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1 Define electricity, and explain different
types of electricity.
2 Explain how electricity is produced.
3 Explain how electricity travels.
4 Explain the difference between conductors
and insulators.
5 Explain circuits, and describe the difference
between an open circuit and a closed circuit.
6 Identify basic electrical safety tips.
Terms. The following terms are presented in this
lesson (shown in bold italics):
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Circuit
Closed circuit
Conductor
Current
Electricity
Electron
Insulator
Matter
Neutron
Open circuit
Proton
Speed of light
Transformer
Voltage
OBJECTIVE 1: Define electricity, and explain
different types of electricity.

I. Electricity is a part of nature. It is all around
us. We cannot see electricity, but we can see its
effect, such as light and heat. Electricity plays a
vital role in the lives of people. It is a necessary
tool in our modern agricultural industry.
OBJECTIVE 1 continued

A. Electricity is a form of energy
produced by the movement of electrons.
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1. Matter is anything that takes up space
or has mass. Everything you can touch is
made of matter. All matter is made up of
atoms.
OBJECTIVE 1 continued
◦ 2. An atom has a center,
called a nucleus. The nucleus
has at least one proton and
one neutron. At least one
electron travels around the
nucleus at a fast rate of
speed.
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a. A proton is a particle with a
positive (+) charge.
b. A neutron is an uncharged, neutral
particle.
c. An electron is a particle with a
negative (–) charge.
OBJECTIVE 1 continued
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When the balance of protons and
electrons is changed by an outside
force, an atom may gain or lose an
electrical charge. This movement of
charge is what we refer to as
electricity.
In September of 1831, Michael Faraday
made the discovery of Electromagnetic Induction.
Faraday attached two wires to a disc and
rotated the disc between the opposing
poles of a horseshoe magnet creating
an electric current.
Electricity
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Electricity is the flow of electrons in a
conductor.
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The electrons must have a path to and
from its source.
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This path is called a circuit.
OBJECTIVE 1 continued
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B. There are two basic types of
electricity: static and current.

1. Static electricity stays in one
place and doesn’t move like current
electricity.
 Electrons DON’T move
 An example of static electricity is the tiny
spark or shock between two people after
they walk or rub their feet across the
carpet.
OBJECTIVE 1 continued
2. Current electricity is a flow of electrical
charge through a substance that conducts
electricity. Two kinds of current electricity
are used:
 a. In direct current (DC) electricity, the
electrons flow in one direction.
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 This type of current is usually produced by
batteries.
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b. In alternating current (AC) electricity,
the electrons flow in alternating directions
and the direction of the current is reversed
many times each second.
 AC electricity comes from power lines.
Electrical Service
Electrical service begins with a power
source, which is usually a large generating
plant with a system of lines to get the
electricity to the user.
 A generator may be used in case of a
power outage, when a loss of power may
result in the loss of life, crops, etc.
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OBJECTIVE 5 continued
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A. A conductor is a material that allows
electricity to easily pass along it or through it.
1. Metals are good conductors because of the
high concentration of free electrons they contain.
 2. Wires used for electrical work are frequently
copper or aluminum because they are good
conductors of electricity.
 3. Water is a conductor of electricity. Things that
contain water (people, animals, trees, etc.) are
also conductors.
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OBJECTIVE 5 continued
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B. An insulator is a material that prevents or
reduces the passage of electricity.
1. Insulators do not allow electrons to flow.
2. Rubber, porcelain, and glass are all good
electrical insulators.
 3. Electric wires are generally covered with a layer
of plastic insulation. A conductor (wire) without
insulation (plastic) is dangerous.
 4. Tools that are commonly used when working
with electricity generally have a layer of plastic
insulation on their handles to prevent a shock.
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OBJECTIVE 2: Explain how electricity is
produced.
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Anticipated Problem: How is electricity produced?
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II. Electric utility power stations use turbines, water wheels, or
some other similar machine to generate electricity. Power
stations must have a source of energy to run the machinery they
use to generate electricity. Most of the electricity in the United
States is produced in turbines driven by steam.
OBJECTIVE 2 continued
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A. Coal can be burned in large furnaces
to heat water to make steam that pushes
the blades of a turbine. More than half
(51%) of the electricity generated in the
United States in 2009 used coal as its
source of energy.
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B. Nuclear power is used to create
steam by heating water through a process
called nuclear fission. Nuclear power
generated 21% of the nation’s electricity
in 2009.
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C. Natural gas can be burned to heat
water for steam, or it can be burned to
produce gases that directly operate a
turbine. Natural gas was used to generate
17% of our electricity in 2009.
OBJECTIVE 3 continued
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A. Electricity leaves the power station and is sent
over lines on tall towers. The very strong current
from a power plant must travel long distances to
get where it is needed. Current is the flow of
electricity through a cable.
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B. Electricity loses some of its strength as it
travels. It must be helped along by transformers,
which boost or “step up” its power. A
transformer is a device that transfers electrical
energy from one circuit to another with a change
in voltage, current, phase, or impedance.
Voltage
The pressure in a circuit that causes the
electrons or current to flow.
 It is sometimes referred to as
electromotive force (EMF).
 A volt is the unit by which electrical
pressure is measured with a voltmeter.
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Voltage
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When electricity must be carried a long
distance through wires, there will be a
decrease in voltage, referred to as voltage
drop.
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Voltage drop occurs due to resistance in
the conductors.
Amperage
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The amount of electrical current flowing
past a point in a circuit.
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Amperage is measured with an ammeter.
OBJECTIVE 3 continued
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C. Before electricity is usable to us, its
voltage must be decreased. Voltage is the
strength of the electricity. Different kinds of
transformers are responsible for “stepping
down” electricity’s power.
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E. When the electricity reaches our homes,
another transformer reduces the electricity
down to just the right level to be used in
our appliances, lights, and other household
items.
OBJECTIVE 3 continued
When a circuit uses too much electricity, an
overcurrent causes a circuit breaker to trip,
shutting down the power to that circuit.
 The service entrance is grounded with a wire
connected to a ground rod driven several feet
into the ground.
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Service Panel
 Follows the meter.
 It houses the circuit breakers for the system
and is used to distribute the power to
individual circuits throughout the system.
Overcurrent
Another type of breaker is a GFCI
(ground-fault circuit interrupter).
 A GFCI is extremely sensitive to circuit
imbalances in order to protect people
who are using electrical devices near
damp areas such as in bathrooms,
kitchens, outside, etc.
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Watts or wattage
 Is
a measure of electrical power.
 Electrical power is work being done by
current(amperage) under
pressure(voltage) in getting the
electrons through the resistance of
wires and machines back to the
generator.
◦ Units of 1,000 watts are called kilowatts.
◦ The relationship between watts(P),
amps(I), and volts(E) is P=I x E.
OBJECTIVE 3 continued
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F. A cable carries the electricity into the
house through a meter that measures how
much electricity is being used.
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G. From the meter, electricity runs through a
meter box throughout the walls into outlets
in the home. The electricity is always waiting
in the wires to be used when something is
turned on.
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H. Electricity travels at the speed of light
(186,000 miles per second).
Next Class…
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Don’t forget your supplies:
2 AA batteries
 Box
 Picture
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National Electrical Code (NEC)
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Guidelines for electrical wiring have been
established by the National Electrical Code
(NEC) to ensure the safe use of electricity.
OBJECTIVE 4: Explain circuits, and describe the
difference between an open circuit and closed circuit.
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IV. Electricity travels in a circuit. A circuit
is a route around which an electrical
current can flow, beginning and ending at
the same point. The word circuit comes
from the word circle.
OBJECTIVE 4 continued
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A. Circuits are formed by wires, appliances, and
other devices.
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B. A circuit requires at least two wires to
handle the flow of the current.
1. One wire (known as “hot”) carries the
current from the source to where it is used.
 2. The other wire (neutral) carries the current
back.
 3. Most electrical circuits also have a third wire
called a ground wire. Ground wires prevent
shock in case the other wires fail, a short
occurs, or excess charge builds up. Ground
wires are attached to metal rods driven into
the ground several feet.
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OBJECTIVE 4 continued
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C. An open circuit is a circuit
that has been disconnected by a
switch or another open in the line.
When you turn a light switch off,
you are opening the circuit.
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D. A closed circuit is a circuit that
is continuously providing a
complete path for the flow of
electricity. When you turn a light
switch on, you are closing, or
completing, the circuit.
OBJECTIVE 6: Identify basic electrical safety tips.
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What are some basic electrical safety tips?
OBJECTIVE 6 continued
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A. Fix or replace loose-fitting plugs
and missing or broken wall plates.
These can overheat and cause a fire.
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B. Use safety covers in all unused
outlets to prevent children from
sticking anything into the outlet.
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C. Do not work with electricity in
damp areas. Never handle electrical
equipment with wet hands or while
standing in a wet or damp place.
OBJECTIVE 6 continued
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D. To help prevent electrocution, a ground fault
circuit interrupter (GFCI) should be used in any
area where water and electricity may come in
contact.
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E. Do not try to fix electrical devices that are not
functioning properly. Let a professional fix them.
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F. Extension cords and electrical appliance cords
with cracks, frays, exposed wires, faulty plugs, poor
insulation, and loose connections should be
immediately replaced or fixed by a qualified
person.
OBJECTIVE 6 continued
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G. Never pull a plug from an outlet while the
equipment is in operation. This creates an arc and
will eventually foul the plug or the outlet, which
can cause electrical shock or a possible fire.
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H. Always unplug items by firmly grasping the
plug itself. Never yank the cord.
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I. Do not hang electrical cords on nails, staple
them to walls or other objects, run them under
carpet or rugs, rest furniture on them, or run
them around pipes.
OBJECTIVE 6 continued
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J. Do not use extension cords as
permanent wiring installations.
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K. Do not overload outlets or power
strips.
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L. Do not leave something plugged in
when it is not in use, unless it is designed
for continuous operation.
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M. Never force a plug into an outlet if it
doesn’t fit.
OBJECTIVE 6 continued
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N. Never let anyone stick anything but a
plug or a cover into an outlet.
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O. Use the correct wattage of light bulb for
the fixture.
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P. Make sure light bulbs are screwed in
securely. Loose bulbs may overheat.
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Q. Never leave a plugged-in appliance where
it might fall into water. If a plugged-in
appliance does fall into the water, NEVER
reach in to pull it out even if it is turned off.
REVIEW
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1. What is electricity? What are the different
types of electricity?
2. How is electricity produced?
3. How does electricity travel?
4. What is a circuit? What is the difference
between an open circuit and a closed circuit?
5. What is the difference between conductors
and insulators?
6. What are some basic electrical safety tips?