You are told to use Gauss' Law to calculate the electric field at a distance [R] away from a charged cube of dimension [a]. Which of the following Gaussian surfaces is best suited for this purpose?

• This field cannot be calculated using Gauss' law
  • The [E]-field from a charged cube is not constant on any of these surfaces.

A charged spherical insulating shell has inner radius [a] and outer radius [b]. The charge density on the shell is [\rho].

What is the magnitude of the [E]-field at a distance [r] away from the center of the shell where [r < a]?

• zero
  • I don't know

A positively charged solid conducting sphere is contained within a negatively charged conducting spherical shell as shown. The magnitude of the total charge on each sphere is the same.

Which of the following statements best describes the electric field in the region between the spheres?

• The field points radially outward.
• The field points radially inward.
  • I do not know.
• The field is zero.

In both cases shown below, the colored lines represent positive (blue) and negative (red) charged planes. The magnitudes of the charge per unit area on each plane is the same.

In which case is the magnitude of the electric field at point P bigger?

• They are the same.
  • I do not know.