Homework Assignment 10
Due Oct. 31, 1997

1. Problem 4.11 from the text.

2. Problem 4.12 from the text. Note: The two spheres are both centered on the origin.

3. The field inside a one-dimensional semiconductor pn junction is

   

   for 0 <= x <= x_n. Here q is the absolute value of the charge of an electron, and N_D is the number of donor impurity atoms per unit volume. Find the charge density.

4. Find the electric field generated by the charge distribution

   

   Find the symmetry in the field, and use Gauss's law to calculate E.

5. The fair-weather electrostatic field above the earth's surface has the empirical form

   

   where a, b, c and d are positive constants and z is the height above the surface.

   • Determine the charge density p(z) as a function of height.
   • Find the total charge within a vertical column from z = 0 to infinity with cross-sectional area A.