1. Electric Field.

2. Electric Field Surrounding any object with charge, or collection of objects with charge, is a electric field. Any charge placed in an electric field will experience a electrical force. We defined the field strength as the electric force per unit charge on any “test charge” placed in the field: E = F / q. E is a vector that points, by definition, in the direction of the net electric force on a positive charge; its units are N / C. F is the vector force on the test charge, and q is the test charge. Some fields are uniform (parallel, equally spaced fields lines) such as the field on the left formed by a sheet of negative charge. Nonuniform fields are stronger where the field lines are closer together, such as the field on the right produced by a sphere of negative charge. q F uniformed field F Nonuniformed field + -- q

3. Electric Field

4. Electrical Potential Difference

5. Electrical Potential Energy If we push the small positive charge close to a positively charges sphere, we will expend energy to overcome electrical repulsion. Work is done in pushing the charge against the electric field of the sphere. This work is equal to the energy gained by the charge. This energy is called electrical potential energy.

6. Electric Potential

7. Electrical Potential Difference

8. Voltage Voltage is commonly used as a short name for electrical potential difference Voltage is commonly used as a short name for electrical potential difference Which means is a measurement of the energy contained within an electric field at a given point Which means is a measurement of the energy contained within an electric field at a given point

9. Accelerators An electric field can be produced by maintaining a voltage difference across any insulating space, such as air or a vacuum. Electric fields are used to create beams of high-speed electrons by accelerating them. Electron beams are used in x-ray machines, televisions, computer displays, and many other technologies.

10. Van de Graaff Generator Example