1. TOC 1 Physics 212 Electric Flux and Gauss Law Electric Flux Gausss Law Electric Field of Spheres Other Gaussian Surfaces Point Charges and Spheres

2. TOC 2 Physics 212 Electric Flux and Gauss Law Flux is defined as the amount of an electric field passing perpendicularly through a surface. For an electric field passing perpendicular to a plane, it is… A E

3. TOC 3 Physics 212 Electric Flux and Gauss Law What if the electric field is not perpendicular? A A θ A E E

4. TOC 4 Physics 212 Electric Flux and Gauss Law What if the surface is a closed surface? q E

5. TOC 5 Physics 212 Electric Flux and Gauss Law In general, Gauss Law states that for any imaginary closed surface Gauss law is always true but not always useful. Q inside is the charge inside the imaginary surface. is the total flux through this surface. We use Gauss law to calculate E. Gauss law is easy to use if the electric field vector is perpendicular to the chosen surface.)

6. TOC 6 Physics 212 Electric Flux and Gauss Law Rules for Conductors All excess charge within a conductor moves to its surface. The electric field inside the material that makes up a conductor is zero. Electric fields just outside the surface of a conductor are perpendicular to its surface. Gausss Law is usually the best way to find the electric field of a conductor.

7. TOC 7 Physics 212 Electric Flux and Gauss Law Q E r The electric flux from Gauss Law The electric field Outside any Sphere A sphere with total charge Q An imaginary Gaussian surface

8. TOC 8 Physics 212 Electric Flux and Gauss Law Q E r The electric flux Gauss Law The electric field Outside any Spherical Shell

9. TOC 9 Physics 212 Electric Flux and Gauss Law Q E r The electric flux Gauss Law The electric field Inside any Spherical Shell R

10. TOC 10 Physics 212 Electric Flux and Gauss Law For a cylinder or a plane, the principal is the same but the surface used changes Note that the end faces must be included unless the cylinder is infinitely long. EnEn EnEn

11. TOC 11 Physics 212 Electric Flux and Gauss Law q Q E r The electric flux Gauss Law The electric field Outside a Conductor with a Point Charge Inside

12. TOC 12 Physics 212 Electric Flux and Gauss Law q Q E r The electric flux Gauss Law The electric field Inside a Conductor with a Point Charge Inside R

13. TOC 13 Physics 212 Electric Flux and Gauss Law Q q E r The electric flux Gauss Law The electric field Outside a Conductor with a Point Charge Outside

14. TOC 14 Physics 212 Electric Flux and Gauss Law Q q E r The electric flux Gauss Law The electric field Inside a Conductor with a Point Charge Outside (it works as a shield and lets no electric field inside its walls) R

15. TOC 15 Physics 212 Electric Flux and Gauss Law Electric Flux Gausss Law Electric Field of Spheres Other Gaussian Surfaces Point Charges and Spheres