Tue. Feb. 3 – Physics Lecture #26 Gauss’s Law II: Gauss’s Law, Symmetry, and Conductors 1. Electric Field Vectors and Electric Field Lines 2. Electric Field and Electric Flux Think about This: Discuss with neighbors

The figure shows three charges that have the same magnitude of charge q. What is the value of the electric flux for each of the five closed surfaces a, b, c, d, and e (shown in cross section) in the figure?

Does Gauss’s law apply to a spherical Gaussian surface not centered on a point charge, as shown in the figure? Would this be a useful surface to use in calculating the electric field? +

A 2.6  C charge is at the center of a cube 7.5 cm on each side. What is the electric flux through one face of the cube? Hint: think about symmetry, and don’t do an integral.

Why can’t you use Gauss’s law to determine the field of a uniformly charged cube? Why wouldn’t it work to draw a cubical Gaussian surface?

A point charge –2Q is at the center of a spherical shell of radius R carrying surface charge density  spread uniformly over its surface. What is the electric field at (a) r = R/2 and (b) r = 2R? (c) How would your answers change if the surface charge density on the shell were doubled?

A point charge –2Q is at the center of a thick metal spherical shell with inner radius R i and outer radius R o. The shell carries a net charge of +Q. a)Determine the electric field everywhere. b)Determine the surface charge density on the inside of the shell and the outside of the shell.

Charge Q is uniformly distributed throughout a sphere radius R. Determine the electric field everywhere.