Types of Charging: 1) When rubbed with silk, copper becomes negatively charged, while lead becomes positively charged. When rubbed with wool, acetate becomes positive, and lead becomes negative. What is the correct order of these materials in the electrostatic series, from loosely held electrons to tightly held? 2) The leaves of a charged electroscope partially collapse as you move your hand nearer to the charged electroscope without touching it. The leaves return to their original position when you move your hand away. This behavior is evidence that: a) your body is an insulator b) a charge was induced on your hand c) the charge was lost to a grounded body d) the charge on the electroscope is negative 3) The bottom of a thundercloud usually becomes negatively charged. Before lightning strikes, the charge of the ground directly beneath the thundercloud will become a) positive by induction b) negative by induction c) positive by conduction d) negative by conduction

Types of Charging: 1) When a glass rod is rubbed with silk, the glass rod acquires a positive charge; when a rubber rod is rubbed with fur, the rubber rod acquires a negative charge. Glass and rubber rods, silk and fur, and a metal-leaf electroscope are on hand. All of them are initially uncharged. a) Explain how you would place a net positive charge on an uncharged electroscope by conduction, and describe the movement of charges that would occur at each stage. You may wish to include appropriately labeled diagrams as part of your explanation. b) Explain how you would place a net positive charge on an uncharged electroscope by induction, and describe the movement of charges that would occur at each stage. You may wish to include appropriately labeled diagrams as part of your explanation. 2) Two neutral objects (X and Y) are placed on a wooden table in contact with each other. A negatively charged rod is brought near object Y, and while the rod is nearby, the metal objects are separated without grounding. Which statement correctly describes what has occurred after the charged rod was removed? a) Object X received a negative charge by conduction, and object Y received a positive charge by conduction. b) Object X received a negative charge by induction, and object Y received a positive charge by induction.

Coulomb’s Law 1) List the similarities and the differences between Newton's Law of gravitation and Coulomb's law of electrostatic force 2) A lead nucleus has the charge of 82 protons. a. What is the direction and magnitude of the electric field at 1.0 x 10-10 m from the nucleus? b. Use Coulomb's law to find the direction and magnitude of the force exerted on an electron located at this distance. 3) The electric force between two charges is 5.6 x 10-3 N. If one of the charge were doubled, and the other tripled and the distance between them reduced to one quarter of the original distance, what would the electric force be between the two charges? Return to day 5