Week 2 (Sept. 2 - 6)
Labor day on Monday, so no class Monday.
Read: Conservation of electric charge (Chap. 3) and Mueschenbroeck's wonderful bottle (Chap. 4)
PHY 202 Lecture: Vector algebra, dot products, work, cross products, torque, Lorentz force law
Read: Conservation of electric charge (Chap. 3) and Mueschenbroeck's wonderful bottle (Chap. 4)
PHY 202 Lecture: Vector algebra, dot products, work, cross products, torque, Lorentz force law
Quiz: None; labor day.
Homework:
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:
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):
Homework:
- Charged spheres (Ex. 3.1),
- Mueschenbroek bottle (Ex. 4.1),
- Potential of N charged spheres (Ex. 4.3*)
- Vector addition (Ex. A.2*)
- 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:
- 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. To prevent unwanted drift in voltage measurements on your electrometer, be sure to have both the electrometer grounded; this can be done by connecting the jack on the side of the electrometer to the third (ground) prong inlet of a wall outlet using a patch cord with banana plugs.
- 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 a 3000 volt 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. To get the best results, be sure that you have both the electrometer and the COM port of the electrostatic power supply attached to earth ground (the ground prong inlet of a wall outlet).
- Parallel plates with constant spacing: For this experiment, keep the metal sphere electrified using the power supply. Attach the electrometer to the parallel plate capacitor. This can be done using the low capacitance test leads; attach the ground clip to the stationary plate and the other (red) clip to the movable plate. Now use the proof plane to gradually scoop charge from the charged sphere onto the movable plate and observe the reading of the electrometer. Be sure to make a data table (and even a plot!) to show how the voltage increases with each ``scoop" when the capacitor plates are separated by a small distance, such as 1 mm. How do things change when you use a 2 or maybe a 4 mm plate separation?
- 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. Now attach the electrometer to the faraday ice pail. Use the proof plane to measure the charge at various locations on the capacitor. How does the charge on the plate depend 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):