## EE 333

**Homework Assignment 12 **

Due Nov. 14, 1997

- Problem 4.23 from the text.
- Problem 4.25 from the text.
- Problem 4.26 from the text.
- Problem 4.27 from the text.
- Problem 4.28 from the text.
- A spherical capacitor consists of a solid metal sphere (r = 0.01 m)
surrounded by a concentric metal sphere (inner radius = 0.02 m, outer radius =
0.021 m). Calculate the capacitance of the spherical capacitor if the medium
between the conductors (the metal sphere and the metal shell) is free space.
- In a very simplistic way, and helicopter can be modeled as a sphere with
a diameter about the size of the chopper. Consider a large helicopter -- it
could be modeled as a sphere with a diameter of, say, about 10 meters.
- What would be its capacitance -- i.e., what is the capacitance of
a metal sphere with a 5 m radius?
- The earth's electric field is about 100 V/m. What is the potential of
a helicopter hovering at an altitude of 30 meters?
- Using the results of (a) and (b), what charge is on a helicopter hovering
at 30 m?

- Consider a charged capacitor with a dielectric slab partially inserted,
as shown below. Find the force on the slab. (Hint: Treat this as two
capacitors: C
_{1} is the capacitance of the part with the dielectric
already inserted, and C_{2} is the capacitance of the part without the
dielectric. Find:

*
Bill Rison,
<rison@ee.nmt.edu >
*