Download - Electric Field - Potential Difference
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is defined as the electric force per
unit charge.
an influence produced by an
electric charge on other charges in
its vicinity.
is a vector field that permeates the
space around electrical charge.
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FORMULAINGETTINGTHEELECTRICFIELD
The electric field (E) is derived in the same way
from the equation:
where:
Q = electric force of one object (C),q = electric force of the other object (C)
d = distance between the two objects (m)
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However, electric field E is a little bit different from
gravitational field g. Gravitational force depends on
mass, whereas electric force does not depend on
mass. Instead, electric force depends oncharges on both objects.
By rearranging the formula, we get:
Electric field (E) for Q:
Electric field for q:
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Let's divide the electric force (F) by charge q:
Therefore, the electric field tells us the force per unit
charge.
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SAMPLEPROBLEMS1. A uniform electric field of magnitude 30 N /
C is directed downward. What are the
magnitude and the direction of the force on
a + 4.0 C charge placed in this electric
field?
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SOLUTION:The electric field is defined as the electric forcedivided by the magnitude of the test charge, so if
we multiply both sides of the equation by the
magnitude of the test charge we can determine the
force.
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ELECTRICFIELDLINES
An electric field can be visualized on paper
by drawing lines of force, which give an
indication of both the size and the strength
of the field. Lines of force are also called
field lines.
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The direction of the field is taken to be the
direction of the force it would exert on apositive test charge. The electric field is
radially outward from a positive charge and
radially in toward a negative point charge.
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ELECTRICALPOTENTIAL
ENERGY
a charge due to its location in an
electric field
a charged object can have potential
energy by virtue of its location in anelectric field
if the charge is released, it will
accelerate in a direction away from
the sphere and its electrical potential
energy will transform into kinetic
energy
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FORMULAINGETTINGTHEELECTRICAL
POTENTIALENERGY
where Kis Coulombs constant.
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POTENTIAL
DIFFERENCEis measured in volts (V).
A potential difference of 1 Vmeans that 1 joule of work is
done per coulomb of charge.
( 1 V = 1 J C-1)
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FORMULAINGETTINGTHEPOTENTIAL
DIFFERENCE
where:
V = potential difference in volts (V)
W = work done or energy transferred injoules (J)
Q = charge in coulombs (C)
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SAMPLEPROBLEMS
1. A charge of magnitude -3.0 x 10-6C is
moved through a potential difference
of 80 volts. Calculate the work done
on the charge.
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SOLUTION
The potential difference can be calculated by
dividing the work done by the size of the charge.
Multiplying both sides of the equation by the size of
the charge allows us to calculate the work done.