A coulomb is a unit of electric charge which protons and electrons attract or repel each other. The protons and electrons being either positive or negative are measured with the formulas +1.6x10-19 C and -1.6x10-19 C. 1 coulomb is equal to the current of one ampere transmitted in one second. The coulomb is symbolized in equations by the uppercase letter C.

Charles-Augustin Coulomb

The Coulomb unit of electric charge was named after a French physicist Charles-Augustin Coulomb. The subsequent law “Coulomb’s law” which explains the force and attraction of electrically charged objects is similarly named.

Charles Augustin De Coulomb
Charles Augustin De Coulomb

Measuring charges

Coulomb’s present a way for science to accurately measure the force of electric charges and their attraction as well as repulsion to each other. Electrically charged objects will either repulse or attract depending on the positivity or negativity of those charges. Electroscopes are early examples of this attract/repel relationship defined by Coulomb.

Pith-ball type of electroscope with an attracting charge.


  1. Beiser, A. (1988). Physical Science (2nd Edition) . New York, NY: McGraw Hill
  2. Image of Charles A. Coulomb (n.d.)
  3. Coulomb's law of force

This WikiPage developed by: Muda White - 2012SP
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