1. Electric Field Models
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.

2. Electric Field Models
The net electric field due to a group of point charges is
where Ei is the field from point charge i.

3. E- Field and G- Field
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

4. Electric Field Lines
What would the electric field lines look like for a uniform electric field?
General Physics 2
Electric Field

5. Electric Field North South East West
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?
North
South
East
West

6. Electric Field 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?
North
South
East
West

7. Electric Field 3.2x10-16, east 3.2x10-16, west 8.0x10-23, east
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?
3.2x10-16, east
3.2x10-16, west
8.0x10-23, east
8.0x10-23, west

8. Calculate the electric field 0.1 m from a 10-6 C charge.
General Physics 2
Electric Field

9. The Electric Field of a Dipole
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.

10. - + Electric Field Lines
Draw field lines for the following charge distributions - +
General Physics 2
Electric Field

11. - - Electric Field Lines
Draw field lines for the following charge distributions - -
General Physics 2
Electric Field

12. The Electric Field of a Dipole
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.

13. EXAMPLE 27.2 The electric field of a water molecule
QUESTION:
1.1 x 10^8 N/C

14. The Electric Field of a Continuous Charge Distribution
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.

15. An Infinite Line of Charge
A very long, thin rod, with linear charge density λ, has an electric field
Where r is the radial distance away from the rod.
Field lines perpendicular to rod surface. Field decreases with distance.

16. Think-Pair-Share
Q1 = -1x10-6 C
Q2 = 10 x 10-6 C
Two charges, Q1 and Q2, are separated by 100 nm. What is the electric field midway between the charges?
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?
General Physics 2
Electric Field

17. Workbook p. 27-3, 27-5, 27-6 Electric Field is a Vector Challenge:
What is the net Electric field at point A?
What is the net force on a charge Q that is placed at A?
Derive the electric field of a line of charge of length L P
Total charge +Q
General Physics 2
Electric Field