1. Ch – 26 Electric Field

2. Electric Field Model • One or more charges (source charges) alter the space around them by creating an electric field, E. • A separate charge (test charge or probe) experiences a force F, exerted by the field. • F = qE

3. Electric Field of a Point Charge • The unit vector points outward from the source charge • If q is negative the vector is reversed and points inward, toward the source charge

4. Electric Field Simulation

5. Electric field of a dipole • Two equal and opposite charges small distance apart • Zero net charge but it causes an E field • Dipole moment: p = qs, pointing from negative to positive

6. Electric Field of a Dipole

7. E Field for an Infinite line of Charge

8. Picturing the Electric Field

9. Electric Field of a Dipole

10. E Field for an Infinite line of Charge

11. Electric Field of a Ring of Charge (Ering)z = [1/(4πε0)] [zQ/(z2+R2)3/2]

12. Electric Field of Charged Disk Limit as R  ∞ Note that this value of E does not depend on the distance from the charged plane (z), only on the surface charge density

13. Electric field strength of an infinitely charged plane is independent of distance from the charge

14. Parallel Plate Capacitor A parallel plate capacitor provides a uniform electric field.

15. Motion of a charged particle in a uniform electric field • a = F/m = qE/m = constant • direction of a parallel to E • charged particle will accelerate/decelerate in the direction of E • projectile motion, if v0 is not parallel to E

16. Motion in a Nonuniform Field • circular motion of a charged particle around a point charge, charged sphere or wire |q|E = mv2/r

17. Simulation lab Simulation lab

18. Superposition problem

19. Earth’s internal structure Figure 1.13

20. Plate tectonics: the new paradigm • Plate boundaries • Types of plate boundaries • Divergent plate boundaries (constructive margins) • Two plates move apart • Mantle material upwells to create new seafloor • Ocean ridges and seafloor spreading • Oceanic ridges develop along well-developed boundaries • Along ridges, seafloor spreading creates new seafloor

21. Figure 15.10a

25. Figure 15.12

27. Plate tectonics: the new paradigm • Plate boundaries • Types of plate boundaries • Convergent plate boundaries (destructive margins) • Oceanic-continental convergence • Denser oceanic slab sinks into the asthenosphere • Pockets of magma develop and rise • Continental volcanic arcs form • Examples include the Andes, Cascades, and the Sierra Nevadan system

28. Figure 15.14a

30. Plate tectonics: the new paradigm • Plate boundaries • Types of plate boundaries • Convergent plate boundaries (destructive margins) • Oceanic-oceanic convergence • Two oceanic slabs converge and one descends beneath the other • Often forms volcanoes on the ocean floor • Volcanic island arcs forms as volcanoes emerge from the sea • Examples include the Aleutian, Mariana, and Tonga islands

31. Figure 15.14b

35. Plate tectonics: the new paradigm • Plate boundaries • Types of plate boundaries • Convergent plate boundaries (destructive margins) • Continental-continental convergence • When subducting plates contain continental material, two continents collide • Can produce new mountain ranges such as the Himalayas

36. Figure 15.14c

39. Plate tectonics: the new paradigm • Plate boundaries • Types of plate boundaries • Transform fault boundaries • Plates slide past one another • No new crust is created or destroyed • Transform faults • Most join two segments of a mid-ocean ridge • Aid the movement of oceanic crustal material

40. Figure 15.16