Students compare the flow of electricity through dry sand, soil, and/or gravel, and sand, soil, and/or gravel saturated with various solutions. The activity could be used to introduce or reinforce the inverse relationship between conductivity and resistance. (author/ts)

Students in electrical trade programs will get the idea of how electrical logging works by doing this simple experiment. By measuring how well electricity flows through underground rock formations, engineers can better understand what is below the surface. Students will need an understanding of the difference between the terms "resistance" and "resistivity," "conductors" and "insulators." Glossary links to the terms used in this experiment are helpful to teachers. Ideas on how to vary the experiment are also helpful. An example of how to make the liquids and an evaluation form is provided.