Module 3
1. Module 3
1.16. Page 7
Module 3—Electrical Phenomena
Lesson Summary
At the start of this lesson you were asked two essential questions:
- What is Coulomb’s Law, and how was this law determined using the results of experiments?
- Can Coulomb’s law predict the effect on electrostatic force if the distance of separation increases by a known amount? What does the answer to this question suggest about lightning safety?
You examined sample data from a Coulomb-type experiment, and you analyzed this data using the techniques of graphical analysis. This work illustrated the essential characteristics of Coulomb’s law:
This law means that if the charges are held constant and the distance of separation increases by some factor, then the effect on the resulting electrostatic force can be predicted. For example, if the distance increases by a factor of four, then the electrostatic force would be 
th its original value. In terms of lightning safety, a wise strategy is to seek low ground—maximize the distance of separation between you and the cloud.
In the next lesson you will continue your work with Coulomb’s law as you consider how much charge is actually transferred in a lightning strike.
Lesson Glossary
Coulomb’s law: the magnitude of the electrostatic force between two charged objects is directly proportional to the product of the two charges on the objects and inversely proportional to the square of the distance of separation between their centres
torsion balance: an instrument designed to measure small forces by the twisting of a thin wire