1. Field Lines

2. Faraday’s Model  The field of a point charge extended vectors into lines radiating from the point.  These are called field lines.

3. Field Lines vs Vector  The electric field is a vector quantity. Measured at each pointMeasured at each point Show magnitude and directionShow magnitude and direction  The field lines connect separate vectors. Show the path of motion for a test chargeShow the path of motion for a test charge

4. Field Line Properties  The field vector is tangent to the field line at each point.  The density of field lines is related to the magnitude of the field.  Field lines cannot cross each other.

5. Dipole  The field lines for two equal and opposite point charges form a special pattern called a dipole.  All the lines start at the positive charge and end at the negative charge.

6. Conductor Fields  Charges move to the surface of a conductor.  The field lines remain perpendicular to the surface of the conductor. True for straight or curved  Inside the conductor the field is zero.

7. Inside Space  The inside of a conductor has no field because the charges have moved to the surface and canceled the field inside.  If there are no isolated charges in a space surrounded by a conductor the field is zero inside.

8. Faraday Cage  The conductor doesn’t need to be solid to block a field.  The enclosure is a Faraday cage. Field between the generators and the cageField between the generators and the cage Not within the cageNot within the cage next