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Coulomb's Law

Set-up used to discharge the charge on the sphere

Equipment provided for the session

Measuring the charge on the sphere

Discharging the sphere

Discharging the sphere

The electrostatic force is one of the fundamental forces of nature, and the strongest that acts over distances larger than the radius of an atom. The properties of the world around us depend on the strength of the electrostatic attraction between protons and electrons. The electrostatic force was first systematically studied by Charles Coulomb in the 1780s. Using very careful measurements of the forces between charged spheres he deduced the law named after him:  

 

The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each charge and inversely proportional to the square of the distance between the charges.
Charles Coulomb
French military engineer and physicist, discoverer of Coulomb's Law

In this experiment you will confirm the inverse square dependence of the electrostatic force by measuring the force between a charged sphere and its image induced in a metal plate. You will also determine the strength of the force - one of the fundamental constants of nature. 

Current students can find more information on Learn Ultra. 

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