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Transcript
Current Electricity
Current electricity refers to the flow of
charged particles from a region of high electric
potential energy to a region of low electric
potential energy.
Try to imagine what your life would be
like without all the devices that run on
current electricity!
Gravitational Potential Energy
When raised up
high, the mass has
a lot of gravitational
potential energy.
When the mass is
released, it
converts its
potential energy
into kinetic energy.
Electric Potential Energy
When held apart, the
positive and negative
charge have a lot of
electric potential energy.
Upon release, the
two charges move
together, converting
their potential
energy into kinetic
energy.
Electric Potential
When you place different amounts of charge
in an electric field, they will each have
different amounts of electric potential energy,
even if you put them in the same place.
Therefore, it is much more convenient to talk
about the electric potential energy per unit of
charge. This is called electric potential.
Differences in electric potential we
know as voltage!
Electrical Pressure
It is much easier to think of voltage as a kind
of electrical “pressure” between two places.
It is caused by a difference in electric
potential energy.
Just as water pressure makes water flow
through a pipe, voltage or electrical
pressure causes electric charges to flow
along a wire.
Water Pressure
Water naturally
flows from the
tank at higher
pressure to the
tank at lower
pressure.
A Complete Circuit
By adding a
pump to put
energy back
into the
system, we
can keep the
water flowing
perpetually.
A Complete Electrical Circuit
Think of the battery as a pump.
Chemical reactions
inside the battery exert
a strong force on the
electrons in the wire,
making them flow out
of the battery, through
the light bulb, and then
back into the battery.
The electrons are never used up. The are
naturally recycled around the circuit.
The Electric Light Bulb
As electrons squeeze
their way through the
thin wire filament of the
light bulb, they bump
into many atoms,
transferring some of
their energy to them.
Their gain in energy makes the filament get hot and
glow. The battery's chemical energy has been changed
to electrical energy which changes to heat and light.
Electric Current
Electric current is defined as the flow of
electric charge.
amount of electric charge
current=
amount of time
Current is measured in amperes.
Electrical Resistance
Different materials are not all equally good at
conducting electricity.
A substance's
resistance is a
measure of
how difficult it
is for electric
current to flow.
Ohm's Law
Resistance is measured in ohms.
V
R=
I
voltage
resistance=
current
Electrical
wire
electrons
voltage
current
resistance
switch
Plumbing
pipe
water
water pressure
gallons per minute
restrictions to flow
faucet or valve