The pith ball experiments described in section 12.1 can be done with homemade equipment. Small, lightly wadded pieces of paper or pieces of Styrofoam torn from a coffee cup can be used in place of the pith balls. These can be tied to pieces of thread and hung from any convenient support. Wooden pencils, plastic pens, or glass stirring rods can be used in place of the rods, and many different kinds of fabric are available in the form of clothing.
a. Using available materials on a dry day, test to see which combinations of rod and fabric produce the best charge when rubbed.
b. Repeat the experiments described in section 12.1. Can you get both types of charge with materials available?