# Week 2

Labor day on Monday, so no class Monday.

Conservation of electric charge (Chap. 3) and Mueschenbroeck's wonderful bottle (Chap. 4)
Quiz: None; labor day.

Homework:
1. Charged spheres (Ex. 3.1),
2. Mueschenbroek bottle (Ex. 4.1),
3. Potential of N charged spheres (Ex. 4.3*)
5. Vector multiplication (Ex. A.3*, Ex. A.4*)

Laboratory:
Capacitance, charge, and electric potential (Ex. 4.2). Be sure to read the introductory paragraphs about the capacitance of a sphere and of parallel plates. Here are a few highlights of the four experiments you'll be performing:
1. measuring charge: in this experiment you will attach the electrometer leads to the faraday ice pail and then insert various charged objects (rubbed silk, plastic, and etc.) into the inner pail so as to measure the relative magnitude and sign (positive or negative) of the charged object
2. charge distribution: here, you will keep the leads of the electrometer attached to the faraday ice pail. On the other side of your desk, you will attach an electrostatic power supply to a metal sphere so as to maintain it at a constant electric potential (voltage). You will then move a second, uncharged sphere, into the vicinity of the electrified sphere and then use the small metal proof plane to explore the second sphere using the faraday ice pail.
3. parallel plates with constant spacing: For this experiment, keep the metal sphere electrified using the power supply. Attach the electrometer to the movable plate of the parallel plate capacitor. Use the proof plane to gradually scoop charge from the sphere onto the movable plate and observe the reading of the electrometer.
4. parallel plates with constant voltage: For this final experiment, remove the power supply from the sphere and instead attach it to the parallel plate capacitor. This will maintain the plates at a constant voltage difference. Attach the electrometer to the faraday ice pail. Use the proof plane to measure the charge at various locations on the capacitor and how this depends on the plate separation.

Supplementary website: This website explains some interesting modern applications of electrostatics like laser and ink-jet printing, electrostatic painting, and air cleaning.

Chapter 3 (4 videos):

Chapter 4 (6 videos):

Physics 2