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Electric Current
Chapter 22-2
What is Electric Current?
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Flow of electric charge
Source of electric energy that can be
controlled
Solids—flowing charges; electrons
Liquids—flowing charges; ions
Measured in units of amperes (A)
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Electric charges will flow continuously
only through a closed connecting loop
called a circuit.
Electric Circuits

Simplest electric circuit
Battery—
source of
electrical
energy
Wire—
electric
conductor
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Current will flow in the circuit as long as
none of the wires (including filament in
bulb) is disconnected or broken.
Working circuit
Broken circuit
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Electrons move away from the negative
battery terminal toward the positive
terminal
Voltage
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Measure of how much electrical
potential energy each electron can gain
Voltage increases—electric potential
energy increases
Measured in Volts (V)
Batteries
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Supplies energy to an electric circuit
When positive and negative terminals are
connected in a circuit, the electric
potential energy is increased
Supplies energy by converting chemical
energy to electric potential energy
Alkaline Batteries
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+/- separated by a moist paste
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Chemical reactions occur in the paste when
a current is added
Produces an electric field in circuit
Batteries contain only a limited amount
of chemicals to produce energy
Once original chemicals are used up—
”dead”
Resistance
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Measure of how difficult it is for
electrons to flow through material
Measured in ohms (Ω)
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Insulators generally have higher
resistance than conductors
Thinner wires—higher resistance
Longer wires—higher resistance
Copper wire—low resistance, good
conductor
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Used in homes because wires do not get hot
enough to cause fire