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📚 College Physics 2e
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1 Introduction: The Nature of Science and Physics2 Kinematics3 Two-Dimensional Kinematics4 Dynamics: Force and Newton's Laws of Motion5 Further Applications of Newton's Laws: Friction, Drag, and Elasticity6 Uniform Circular Motion and Gravitation7 Work, Energy, and Energy Resources8 Linear Momentum and Collisions9 Statics and Torque10 Rotational Motion and Angular Momentum11 Fluid Statics12 Fluid Dynamics and Its Biological and Medical Applications13 Temperature, Kinetic Theory, and the Gas Laws14 Heat and Heat Transfer Methods15 Thermodynamics16 Oscillatory Motion and Waves17 Physics of Hearing18 Electric Charge and Electric Field19 Electric Potential and Electric Field20 Electric Current, Resistance, and Ohm's Law21 Circuits and DC Instruments22 Magnetism23 Electromagnetic Induction, AC Circuits, and Electrical Technologies24 Electromagnetic Waves25 Geometric Optics26 Vision and Optical Instruments27 Wave Optics28 Special Relativity29 Quantum Physics30 Atomic Physics31 Radioactivity and Nuclear Physics32 Medical Applications of Nuclear Physics33 Particle Physics34 Frontiers of Physics

Chapter 18: Electric Charge and Electric Field

A child swoops down a plastic playground slide, his hair standing on end.
Figure 18.1 Static electricity from this plastic slide causes the child’s hair to stand on end. The sliding motion stripped electrons away from the child’s body, leaving an excess of positive charges, which repel each other along each strand of hair.Static electricity from this plastic slide causes the child’s hair to stand on end. The sliding motion stripped electrons away from the child’s body, leaving an excess of positive charges, which repel each other along each strand of hair. (credit: Ken Bosma/Wikimedia Commons)

The image of American politician and scientist Benjamin Franklin (1706–1790) flying a kite in a thunderstorm is familiar to many schoolchildren. (See Figure 18.2.) In this experiment, Franklin demonstrated a connection between lightning and static electricity. Sparks were drawn from a key hung on a kite string during an electrical storm. These sparks were like those produced by static electricity, such as the spark that jumps from your finger to a metal doorknob after you walk across a wool carpet. What Franklin demonstrated in his dangerous experiment was a connection between phenomena on two different scales: one the grand power of an electrical storm, the other an effect of more human proportions. Connections like this one reveal the underlying unity of the laws of nature, an aspect we humans find particularly appealing.

Benjamin Franklin is shown flying a kite and lightning is observed. A metal key is attached to the string.
Figure 18.2 When Benjamin Franklin demonstrated that lightning was related to static electricity, he made a connection that is now part of the evidence that all directly experienced forces except the gravitational force are manifestations of the electromagnetic force.

Adapted from College Physics 2e by OpenStax (openstax.org), licensed under CC BY-NC-SA 4.0. Changes were made. License: CC-BY-NC-SA-4.0.