Download Introduction to Atom and Electricity

9/6/2016
Structure of an atom
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Electrons (-) rotate in orbit around the nucleus.
Protons (+) and Neutrons (no charge) are
found in the nucleus.
The nucleus is located in the center of the atom.
Electrons (-) rotate in orbit around the nucleus.
Protons (+) and Neutrons (no charge) are
found in the nucleus.
The atom contains an equal number of
electrons and protons making its combined
electric charge zero.
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Electrons are arranged in shells around the nucleus.
Nucleus Electron Spacing
The shells are identified by numbers or letters.
• If the nucleus was expanded to the size of
a marble, the outer edge of the atom
would be nearly a football field away
There are a
maximum number
of electrons that
can be contained in
each shell.
Foot ball field
Marble Size
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Placement of electrons in a copper atom
It is possible, through the action of some outside
force, for an atom to lose or acquire electrons.
3 (+)
2 (-)
3 (+)
4 (-)
A negatively
charged ion is an
atom that has
acquired electrons.
3 (+)
3 (-)
A positively
charged ion is an
atom that has lost
electrons.
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Whenever a valence electron is removed from its
orbit, it becomes a free electron.
The outermost shell or
highest energy level of the
atom is called the valence
shell, and its electrons are
called valence electrons.
Valence electrons can become free of their orbit by
the application of some external force such as
friction or voltage.
Electricity can be
defined as the flow of
free electrons from
atom-to-atom through
a conductor.
The number of valence electrons in a given atom
determines its ability to gain or lose an electron,
which in turn determines the electrical properties
of the atom.
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A material is said to conduct electricity when one
electron of an atom is forced from its orbit path by
another atom’s electron.
Materials that permit free electrons to move easily
from one atom to another are called conductors.
Conductors offer very little resistance to the flow
of electrons through them.
Most metals are good conductors of
electricity. Copper is the most
common metal used as a conductor of
electricity.
When one electron strikes another, the electron
being hit takes energy from this action and jumps
to a neighboring electron’s orbit.
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Conductors have very few electrons in their
outer valence shell resulting in them being easily
knocked out of the atom’s orbit.
Insulator is the name given to a material through
which it is very difficult to produce a flow of
electrons.
Aluminum Atom
Generally, a good
conductor has an
incomplete valence
shell of one, two, or
three electrons.
Insulators have few, if any, free electrons and resist
the flow of electrons.
Insulated copper conductors
are used to keep electrons
flowing along the intended path
of a circuit.
Valence shell is incomplete
with only 3 out of possible
18 electrons.
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No material has been found to be a perfect
insulator.
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A semiconductor is a
material that has some of the
characteristics of both a
conductor and an insulator.
Every material can be forced to permit a small
flow of electrons from atom to atom if enough
energy in the form of voltage is applied.
Examples of pure semiconductor materials are
silicon and germanium.
Whenever a material that is classified as
an insulator is forced to pass an electric
current, the insulator is said to have
been broken down or ruptured.
They are not naturally semiconductors but can be
made into semiconductors (p-type or n-type) by
melting them and adding very small amounts of
other chemicals.
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A diode is one of the simplest
semiconductor components.
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When connected in reverse-bias to the battery
voltage, the diode acts as an insulator and blocks
current flow to the lamp.
The main characteristic of a diode is its ability to
pass electron current flow in one direction only.
When connected in
forward-bias to the
battery voltage, the
diode acts as a
conductor and conducts
current flow to the lamp.
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This tester is designed for checking electric
components out of their normal circuits.
When an electric circuit is capable of conducting
current, it demonstrates electrical continuity.
Continuity
test circuit
A flow of electrons that
causes the lamp to come
on at full brightness.
An open in the conductor
path produces no flow of
electrons or light from
the bulb.
Under no circumstances should the continuity
tester be connected to a circuit where other
sources of higher voltages may be present!
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Electronics refer to the appliances and
devices that are powered and run by electricity. The
electronic devices are so made that they draw
electricity from the source of power and manage
the flow within them using electronic components.
Electric or electrical are terms that can be used
interchangeably because they relate to the
concept of electricity.
The word electric is used in
the sense that it states the flow
of electricity. Thus the term
electric or electrical refers to
the source and usage of
power when it is conducted
through a device.
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Electric motor
A printed circuit board
assembly is a selfcontained module of
interconnected electronic
components found in
most electronic devices.
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