Peoples Physics Concepts

12.1. Electrostatics http://www.ck12.org

12.1 Electrostatics

• Describe the basics of electrostatics.

Students will learn the inner workings of electrostatics: Why certain objects repulse, why certain objects attract and
how to calculate the number of excess electrons or protons in an object.

Key Equations

q=Ne Any object’s charge is an integer multiple of an electron’s charge.

Guidance

• Opposite charges attract and like charges repulse


• The electron (and proton) is the fundamental charge unit. The charge of an electron and proton is 1. 6 × 10 −^19
  C. One can determine the number of excess electrons (or protons if positive charge) by dividing the objects
  charge by the fundamental charge.


• Most objects are electrically neutral (equal numbers of electrons and protons) and that’s why gravity dominates
  on a macro scale.

Example 1

QuestionIf an object has +0.003 C of charge, how many excess protons does the object have?

Answerq=Ne 0 .003C=N× 1. 6 × 10 −^19 N = 1. 875 × 1016 ; protons

Watch this Explanation

MEDIA

Click image to the left for use the URL below.

URL: http://www.ck12.org/flx/render/embeddedobject/1865