Chapter
15 & 16
Electrostatics:
Forces & Energy
Electric
Field
**Definition
of the Electric Field**,
If
a test charge experiences
a force at
a given location, the electric field at
that location is
Units:
N/C
The
electric field is the force per charge at a given location.
Video of Electric Field
Solving
for the force gives us the force on a given charge:
Example
15-10
In
a certain region of space, a uniform electric field has a magnitude
of and
points in the positive x direction. Find the magnitude and direction
of the force this field exerts on a charge of **(a)** +2.80 µC
and **(b)** -9.30 µC.
Solution:
(a)
(b)
Electric
Field of a Point Charge
**Magnitude
of the Electric Field Due to a Point Charge**
Example
15-11
Find
the electric field produced by a 1.0 µC point charge at a distance
of **(a)** 0.75 m and **(b)** 1.5 m.
Solution:
(a)
(b)
Example
15-12
Two
charges, and ,
have equal magnitudes q and are placed as shown in the figure. The
net electric field at point P is vertically upward. We conclude that
**(a)** is
positive, is
negative; **(b)** is
negative, is
positive; or **(c)** and have
the same sign.
Solution:
(b) is
negative, is
positive.
Example
15-13
Two
charges, each equal to +2.90 µC, are placed at two corners
of a square 0.500 m on a side, as shown. Find the magnitude and
direction of the net electric field at a third corner of the
square, the point labeled 3 in sketch.
Solution:
On to Electric Field Lines |