Transcript Sources of Electricity

Sources of Electricity
Electronics 1
CVSD
Resistance
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A measure of the opposition to the flow of
electrons through a material
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Unit of Measurement:
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Ohm (Ω)
Symbol:
–
R
Voltage
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A measure of the Electromotive Force that pushes
electrons through a circuit (Potential Difference)
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Unit of Measurement:
–
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Volt (V)
Symbol:
–
E
Current
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A measure of the Intensity or total amount of
electrons flowing in a circuit in a given unit of time
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Unit of Measurement:
–
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Ampere (A)
Symbol:
–
I
Power
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A measurement of the rate of consuming energy,
transferring energy, or doing work
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Unit of Measurement:
–
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Watt (W)
Symbol:
–
P
Six Sources of Electricity
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Chemical
Magnetic
Friction
Pressure
Heat
Light
Chemical
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Uses unlike materials (electrodes) in a solution
(electrolyte) to form a “voltaic cell”
Cell: Two electrodes with an
electrolyte in between
Battery: Multiple cells strung
together in series &/or parallel circuits
Primary cell = cannot be recharged
Secondary cell = can be recharged
Cells can be “wet” or “dry”
(refers to electrolyte)
Magnetic
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Uses a conductor “armature” passing through a
magnetic field (lines of flux)
As the conductor “cuts” through the lines of flux, a
voltage is produced (electrons attracted to or repelled
by the field)
Used in generators
to convert mechanical
energy into
electrical energy
Amount of current
produced depends on speed
of armature & # of coils in the armature
Friction
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Electrical charge can be produced from rubbing certain
unlike materials together (electrons transfer from one
of the materials to the other)
Called “static electricity”
The release of this “static charge”
results in a static shock (lightning,
when you shock yourself
on metal, etc)
Friction between the touching
surfaces often causes heat
(helps transfer electrons)
Pressure
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Some materials will transfer an external
pressure to their internal atoms, which drives
their electrons out of orbit (causing an electric
charge)
Most common material = crystals
Used in microphones and
phonograph pickups
Convert mechanical energy
into electrical energy
Heat
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Two unlike pieces of metal joined together
produce electricity when heated
Called a “thermocouple”
Current depends on the amount of heat &
types of metals used
Converts thermal energy into electrical energy
Used in conjunction with a ammeter to make a
pyrometer (measures high temperatures)
Light
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When light hits certain materials it releases electrons,
causing an electric charge.
Main principle behind solar
cells (photo voltaic cell)
Solar cells are made of
silicon, when light waves
hit the silicon they release
electrons
Convert light energy into
electrical energy
Amount of current depends on amount of light
Review
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Voltage is:
Current is:
Resistance is:
Power is:
What are the six sources of electricity?
List the principle parts of a voltaic cell
Lightning comes from which source?
What is the difference between a primary and
secondary cell?