Download The electric field of a point charge q at the origin, r = 0, is

The electric field of a point charge q at the origin, r = 0, is
where є0 = 8.85 × 10–12 C2/N m2 is the permittivity constant.
The direction of field determined by motion induced on a
positive test charge.
The net electric field due to a group of point charges is
where Ei is the field from point charge i.
•  Electric field is electric force per unit charge.
What is the analogous quantity for
gravitational force? Derive a mathematical
expression for gravitational field. Have you
seen this quantity before?
General Physics 2
Electric Field
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Electric Field Lines
•  What would the electric field lines look like
for a uniform electric field?
General Physics 2
Electric Field
4
A proton is released in a uniform electric field, and it
experiences an electric force toward the south. What is the
direction of the electric field?
1. 
2. 
3. 
4. 
North
South
East
West
An electron is released in a uniform electric field, and it
experiences an electric force toward the west. What is the
direction of the electric field?
1. 
2. 
3. 
4. 
North
South
East
West
What are the magnitude and direction of the electric force on an
electron (e=1.6x10-19 C) in a uniform electric field of strength
2000 N/C that points due east?
1. 
2. 
3. 
4. 
3.2x10-16, east
3.2x10-16, west
8.0x10-23, east
8.0x10-23, west
•  Calculate the electric field 0.1 m from a 10-6 C
charge.
General Physics 2
Electric Field
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We can represent an electric dipole by two opposite charges
±q separated by the small distance s.
The dipole moment is defined as the vector
The dipole-moment magnitude p = qs determines the
electric field strength. The SI units of the dipole moment
are C m.
Electric Field Lines
•  Draw field lines for the following charge
distributions
-
General Physics 2
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Electric Field
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Electric Field Lines
•  Draw field lines for the following charge
distributions
-
General Physics 2
-
Electric Field
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The electric field at a point on the axis of a dipole is
where r is the distance measured from the
center of the dipole.
The electric field in the plane that bisects and is
perpendicular to the dipole is
This field is opposite to the dipole direction, and
it is only half the strength of the on-axis field at
the same distance.
QUESTION:
The linear charge density of an
object of length L and charge
Q, is defined as
Linear charge density, which
has units of C/m, is the amount
of charge per meter of length.
A very long, thin rod, with linear charge density λ,
has an electric field
Where r is the radial distance away from the rod.
Think-Pair-Share
Q1 = -1x10-6 C
•  Two charges, Q1 and
Q2, are separated by
100 nm. What is the
electric field midway
between the charges?
General Physics 2
Q2 = 10 x 10-6 C
•  Two charges, Q1 and
Q2, are separated by
100 nm. Where on the
line joining Q1 and Q2
is the electric field equal
to zero?
Electric Field
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Workbook p. 27-3, 27-5, 27-6
Electric Field is a Vector
•  What is the net Electric field
at point A?
•  What is the net force on a
charge Q that is placed at
A?
Challenge:
•  Derive the electric field of a
line of charge of length L
Total charge +Q
P
General Physics 2
Electric Field
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