1. ELECTRIC FIELDS

2. CREATING AND MEASURING ELECTRIC FIELDS Michael Faraday developed the concept of an electrical field where electrical charges exert forces on other charges. An electrical field describes how a charged particle affects the motion of other charged particles around it. Electrical field lines can be drawn to indicate magnitude and direction of the field. Point away from (+) charged particles and toward (-) charged particles If the field lines are close together, this indicates the stronger area of the field. And if they are farther apart, the weaker area.

3. ELECTRIC FIELD LINES

4. CREATING AND MEASURING ELECTRIC FIELD

6. APPLICATIONS OF ELECTRIC FIELDS 1913, Robert Millikan determined charge of an electron through experiment with charged oil drops in an electric field. Also discovered the electrical charge is quantized.

7. APPLICATION OF ELECTRIC FIELD Chamber contains 2 horizontal metal plates connected to a battery. Top plate is (+) charged, bottom is (-) charged, creating a downward electric field between plates. Electric field can be adjusted by controlling voltage across plates. Atomizer sprays in tiny oil drops. X-ray source used to ionize air molecules and drops. Microscope positioned outside chamber magnifies locations of individual drops.

8. APPLICATION OF ELECTRIC FIELD When the electric field is turned on, some of oil drops start to rise because of electric force on the drop becomes greater than force of gravity. If set just right, an oil drop can actually be suspended in the chamber. At this point electric force is equal to force of gravity. Using a modified equation to calculate the electric charge on the drop of oil, Millikan repeated the experiment with many drops of oil. He found that the charge of each drop continually worked out to be a multiple of one fundamental value, which is the charge of an electron.

9. APPLICATION OF ELECTRIC FIELD The experimental value that he calculated for the charge of an electron is within 1% of the accepted value for the charge of an electron used today. Accepted value of electron+ 1.6021765x10 -19 C