Transcript File

Electric Field
Physics
Mrs. Coyle
Coulomb’s Law
Practice Problem
 Suppose that two point charges, each with a
charge of +1.00 Coulomb are separated by a
distance of 1.00 meter. Determine the
magnitude of the electrical force of repulsion
between them.
Analogy
The electric field is the space
around an electrical charge
just like
a gravitational field is the space
around a mass.
Electric Field
 Space around a charge.
What is the difference?
Van de Graaff Generator
 Builds up static electric
charges.
 https://www.youtube.com/wat
ch?v=rNEY3Yv9kC8
Electric Field Vector, E
 E = F/ qo
 qo , positive test charge
 E is a vector quantity
 Unit: N/C
 E is analogous to the gravitational
field, g, where g=F/m
Example 1
 A charge of 3µC is used to test the electric
field of a central charge of 6C that causes a
force of 800N. What is the magnitude of the
electric field?
Electric Field Lines
Electric Field Lines of two Positive
Charges
Electric Field Lines
 Lines that indicate the strength and
direction of the electric field.
 The more dense the lines, the stronger the
field.
 Electric field vectors are tangent to the
curve.
 Simulation
http://online.cctt.org/physicslab/content/applets/
pointcharges/elefi_z.htm
Why can you not get radio
reception in a tunnel or in a steel
bridge?
Which field is stronger?
A
B
Example 2
 A test charge of +3µC is located 5m to the
east of a -4µC charge.
 A) Find the electric force felt by the test
charge.
 B) Find the electric field at that location.
Example 4
 Calculate the electric field felt by a test charge
located half way between a charge of +1C and
a charge of -3C, that are 2m apart.