Electric Field - Potential Difference

8/13/2019 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.

Electric Field - Potential Difference

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