1. Movement of Charges in an Electric Field

2. Millikan had charges suspended between electric plates.

3. This meant that the forces were balanced.

4. If the forces are not balanced, there will be a net force on the charge, causing acceleration

5. Using this net force and acceleration we can solve problems for motion in the electric field.

6. First consider a line of charge and a single point charge placed nearby. The horizontal components of corresponding charges cancel and the vertical components add.

7. For oppositely charged plates, the effect is enhanced.

8. The field is constant and is directed from the positive to the negative plate. The edges of the field bulge slightly since there are no charges outside the plates to balance the horizontal effects of the nearby charges.

9. For simplicity, we will assume that the field between plates is constant throughout.

10. Sample problems