Electric Current
Types of Electric Current
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Electric current is a continuous flow of
electric charge and is measured in
Amperes (A).
The two types of electric current are
direct current and alternating
current.
Direct Current
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Electric charge that only flows in one
direction is direct current.
A battery is a device that changes
chemical energy to electrical energy.
A battery has a negative terminal and a
positive terminal
• The charge moves from the negative terminal
to the positive terminal.
Alternating Current
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A flow of electric charge that regularly
reverses its direction is known as
alternating current.
AC offers an advantage in transporting
electric current over long distances.
• AC electricity in the US changes direction 60
times each second.
“War of Currents”
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AC: Tesla/Westinghouse
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DC: Edison/General Electric
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AC wins due to long range transmission
and transformers
Conductors
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A conductor is a material through
which charge can easily flow.
• Metals, such as, copper, silver, and
aluminum are good conductors.
Insulators
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A material through which charge cannot
easily flow is called an insulator.
• Wood, rubber, and Styrofoam are good
insulators.
Resistance
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Resistance is the opposition to
movement of charge through a material.
Measured in units called ohms (Ω)
What effects resistance of a material
• Its size (thick wire < thin wire)
• Shape (long wire > short wire)
• Temperature (hot wire > cool wire)
Voltage
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Electric current flows because of
differences in electric potential, called
voltage.
Electric Potential: The electric energy
per charge.
Potential Difference: Difference in
electric potential between two places in
an electric field.
Voltage Source
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Electric Current requires continuous
voltage
Ohm’s Law
V=IR (v=voltage, I=current,
R=resistance)
Labels: Voltage (volts), Current (amps),
and Resistance (ohms)