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Electric Circuits and
Electric Current
A flashlight, an electric toaster, and a car’s
starting motor all involve electric circuits and
electric current.
For the flashlight bulb
to light, there must be
a
closed
or
complete
path
from the bulb to
both ends of the
battery.
Such a path is called
a
circuit
.
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View Full Document Electric Circuits and
Electric Current
A flashlight, an electric toaster, and a car’s
starting motor all involve electric circuits and
electric current.
In this circuit, the battery is the energy source,
using energy from chemical reactions to separate
positive and negative charges.
This leads to a voltage difference, with an excess
of positive charges at one end of the battery and
an excess of negative charges at the other.
These charges will tend to flow from one terminal
to the other if we provide an external conducting
path (the
circuit
).
A flow of electric charge is an
electric current
:
where
I
is electric current,
q
is charge,
and
t
is time.
The standard unit for electric current is the
ampere
:
1 A = 1 C / s
I
q
t
For example, if 3 C of
charge flow through a wire in
2 s, then the electric current
I
is
3 C / 2 s = 1.5 A
.
Positive charges moving to
the right have the same
effect as negative charges
moving to the left.
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View Full Document
A flow of electric charge is an
electric current
:
where
I
is electric current,
q
is charge,
and
t
is time.
The standard unit for electric current is the
ampere
:
1 A = 1 C / s
I
q
t
The direction of current is
defined as the direction that
positive charges would flow.
In reality, the charge
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This note was uploaded on 04/23/2011 for the course PHYS 214 taught by Professor Staff during the Spring '08 term at Purdue UniversityWest Lafayette.
 Spring '08
 Staff
 Current, Light

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