1. 18.1 Electrical Potential Energy pp. 666 - 669 Mr. Richter

2. Agenda  Warm-Up  Additional Homework  Electric Field Lines (17.3)  Notes:  Electrical Potential Energy  Calculating Electrical Potential Energy  In Uniform Electric Fields  From a Single Charge

3. Objectives: We Will Be Able To…  Define electrical potential energy.  Calculate electrical potential energy.

4. Warm-Up:  A positive and a negative charge are separated from each other and held apart. How is this similar to a stretched rubber band?

5. Electric Field Lines

6.  To visualize the electric field, electric field lines are drawn.  Rules:  Lines are drawn from positive charge to negative.  Number of lines drawn in proportional to strength of charge.  Lines do not cross.

7. Electric Field Lines  Electric field lines show the combinations of electric fields from more than one charge.  Opposite, equal charges.

8. Electric Field Lines  Electric field lines show the combinations of electric fields from more than one charge.  Like, equal charges.

9. Electric Field Lines  Electric field lines show the combinations of electric fields from more than one charge.  Opposite, unequal charges.

10. Electrical Potential Energy

11.  An object some distance above the ground wants to fall. It has gravitational potential energy.  If a charge experiences a force (attraction or repulsion), it similarly wants to move.  Electrical potential energy (PE electric) ) is the energy stored in an object due to its position relative to a source of electric force.

12. Electrical Potential Energy: Uniform Electric Field

13.  A uniform electric field exists when all charges experience the same force (magnitude and direction) in the field.  A charge’s potential energy in the field depends on its distance from the source of electric force.  Just like the gravitational potential energy of an object depends on its distance above the ground.

14. Electrical Potential Energy: Uniform Electric Field  Just like with other forms of potential energy, it’s really the change in position that is important.  Remember:  Energy = Work = Force x displacement

15. Electrical Potential Energy: A Pair of Charges

16.  A single charge can also give potential energy to another charge.  Again: Work = Force x Distance

17. Wrap-Up: Did we meet our objectives?  Calculate electric force using Coulomb’s law.  Calculate electric field strength.  Draw and interpret electric field lines.  Define electrical potential energy.  Calculate electrical potential energy.

18. Homework  All due tomorrow!  p. 636 #3, 4  p. 656 #41, 42  p. 657 #55  p. 669 Practice #2, 4  p. 669 Section Review #5, 6