Electric Fields 21.1
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Transcript Electric Fields 21.1
Electric Fields
Chapter 21
21.1 Creating & Measuring Electric
Fields
The electric force varies inversely as the
square of the distance between two point
objects.
How can a force be exerted through empty
space?
Michael Faraday suggested because of an
electrically charged object changing the
properties of space
Electric Field
The changed property of space is the electric
field
The electric field means that the interaction is
not between two objects, but between an
object and the field at the location of the
object.
Electric Field
How is the electric field measured?
Place a small positively charged object in the
space, if there is a force on the object, there
is an electric field.
According to Coulomb’s law the force and the
charge are directly proportional.
So divide F by q (test charge) and get a
vector quantity representing the electric field
at a certain point.
Electric Field Strength
The direction of an
electric field is the
direction of the force
on a positive test
charge.
The magnitude of
the electric field is
measured in N/C.
E
Fonq'
q'
Picturing the Electric Field
Electric field is a vector quantity so use an
arrow to represent the direction of a positive
test charge and the number of arrows and
spacing between lines represent the strength
These are electric field lines