# Unit 4: Electromagnetics | Physics Web Links

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## Chapter 18: Electric Charge

• Charles Du Fay—This is a biography of Charles Du Fay.
• Millikan’s Oil Drop Experiment—Access a reproduction of Millikan's original oil-drop experiment paper in The Physical Review.
• Electrostatic Detectors—This resource will fill in students’ understanding of charge detectors. Many photos of various forms of static charge detectors are provided.

## Chapter 19: Electric Fields

• Capacitor Theory—This site provides interesting  information on capacitor construction and theory. (Note: This site is principally about the theory and construction of an operational, home-built coil gun. The device itself is potentially dangerous. Use your judgment when sharing this material with your students.)
• Build Your Own Capacitor—Make your own capacitor or Leyden jar. The page links back to the site’s High Voltage experiment home page, which provides other interesting experiments in high voltage. Again, caution is advised.

## Chapter 20: Electrodynamics

• Ohm's Law—This is a useful interactive Java applet investigation of Ohm's law using various combinations of resistors.
• Kirchhoff's Rules—This resource provides many sample circuit analysis problems for applying Kirchhoff's rules.

## Chapter 21: Magnetism

• Magnetic Anomalies—The link opens a detailed USGS map of magnetic features in North America and the surrounding oceans.
• Velocity Selector—This features an interactive animation that requires the student to compute the correct particle velocity for the velocity selector settings.

## Chapter 22: Electromagnetism

• Lorentz Force—This link connects to an interactive animation demonstrating the action of the electromagnetic force on a conductor. The Lorentz force is the formal name for the magnetic force on a conductor discussed in the text.
• Motors and Generators—This is an interactive animated demonstration of the electrical principles of simple and complex electric motors and generators.
• Paperclip Motor—This link connects to a teacher's guide for building an operational DC motor from locally obtainable materials, and the principles upon which it operates.