Chapter 18 review


    Conceptual questions
      Section 18.2
      1. Which equation below correctly matches the meaning of this sentence: “The electrostatic force between two charged particles equals the product of their charges divided by the square of the distance between them, all multiplied by a constant.”
        1. F= k e q 1 q 2 r
        2. F= k e ( q 1 q 2 r ) 2
        3. F= k e q 1 q 2 r 2
        4. F= k e q 1 2 q 2 2 r
      2. Lightning carries enormous electrical energy. What are the electrical characteristics of lightning bolts? How do they form? Use advanced searches to gather information from multiple authoritative sources. Integrate the information into a cohesive scientific narrative. Include an assessment of the strengths and limitations of each source.
      3. When the leaves of an electroscope repel one another, do they have like or unlike charges?
      4. Easy Why do charged objects seem to hold more static charge in the winter?
      5. Easy What causes clothes to cling together when removed from a dryer?
      6. Easy Is it required for a charged object to touch the ball of an electroscope for its leaves to spread?
      7. Easy Describe three differences between the electric force and the gravitational force.
      8. Easy What is the relationship among electric charge, distance, and electric force?
      9. Easy If two charged objects are moved to twice the separation, how does the mutual electric force between them change?
      10. Easy If the distance between two charged objects is halved, how does the mutual electric force between them change?
      11. Easy What is happening when we ground an object (or connect it to ground)?
      12. Easy Gratia rubs two balloons against her sweater and discovers that the balloons attract her hair. Will the balloons attract or repel each other or neither?
      13. Easy What weather conditions are conducive to static electricity buildup?
      1. Easy How can you use an electroscope to determine whether an object were electrically charged or neutral?
      2. Medium How can you charge an object with positive charges only using another object that has negative charge?
      3. Medium Two objects experience a mutual electrical force equal to their mutual gravitational force. If they are moved to twice the distance apart, what is the new relationship between their mutual electrical and gravitational forces?
      4. Medium How can you use an electroscope to determine whether two electrically charged objects have the same polarization, i.e., the same sign for their net charge?
      5. Medium Why are electric charges distributed on the surface of a metal sphere rather than throughout its interior?
      6. Medium A small Van de Graaff generator might have a voltage of a thousand volts or more. Why don’t people die when they touch it in a lab?
      Section 18.3
      1. An isolated, positively charged sphere creates an electric field in the surrounding region of space. The electric field has a value of E1 at a distance of 1 m from the charge.
        1. If you double the distance to 2 m, by what factor does E change?
        2. If you triple the distance to 3 m, by what factor does E change?
        3. At what distance from the charge is the field equal to zero?
      2. Easy List three kinds of force fields.
      3. Easy List three examples of contact forces, and three examples of noncontact forces.
      4. Easy Sketch the electric field around two identical, positively charged particles separated by a small distance.
      5. Easy An electric force field diagram is composed entirely of arrows pointing from left to right. In what direction will a negatively charged object feel an electric force?
      6. Easy The electric field around a charged object has field lines that, everywhere on its surface, point toward its center. What is the sign of its electric charge?
      7. Easy A 1 C charge placed at a given point in space feels a force of 100 N.
        1. What force would be felt by a 2 C charge placed at this same location?
        2. What force would be felt by an 0.5 C charge placed at this same location?
        3. What is the magnitude of the electric field at this location?

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