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Chapter 18 | Electric Charge and Electric Field 793
Figure 18.16
Solution
Water molecules are polarized, giving them slightly positive and slightly negative sides. This makes water even more susceptible to a charged rod's attraction. As the water flows downward, due to the force of gravity, the charged conductor exerts a net attraction to the opposite charges in the stream of water, pulling it closer.
Applying the Science Practices: Electrostatic Induction
Plan an experiment to demonstrate electrostatic induction using household items, like balloons, woolen cloth, aluminum drink cans, or foam cups. Explain the process of induction in your experiment by discussing details of (and making diagrams relating to) the movement and alignment of charges.
PhET Explorations: John Travoltage
Make sparks fly with John Travoltage. Wiggle Johnnie's foot and he picks up charges from the carpet. Bring his hand close to the door knob and get rid of the excess charge.
Figure 18.17 John Travoltage (http://cnx.org/content/m55301/1.2/travoltage_en.jar)
18.3 Conductors and Electric Fields in Static Equilibrium
Learning Objectives
By the end of this section, you will be able to:
• List the three properties of a conductor in electrostatic equilibrium.
• Explain the effect of an electric field on free charges in a conductor.
• Explain why no electric field may exist inside a conductor.
• Describe the electric field surrounding Earth.
• Explain what happens to an electric field applied to an irregular conductor.
• Describe how a lightning rod works.
• Explain how a metal car may protect passengers inside from the dangerous electric fields caused by a downed line
touching the car.
The information presented in this section supports the following AP learning objectives:
• 2.C.3.1 The student is able to explain the inverse square dependence of the electric field surrounding a spherically symmetric electrically charged object.
• 2.C.5.1 The student is able to create representations of the magnitude and direction of the electric field at various