(1) Find a piece of waste plexiglass, cut it into two pieces of glass with a length of 12cm and a width of 1- 1.scm, and two waste toothbrushes (same color, transparent _); An old silk and a plastic film, one foot square. The friction between plexiglass and silk is positive, and the friction between toothbrush handle and silk is negative. The friction of plastic thin plexiglass is also negatively charged, but it is more powerful than that of silk friction, so it is suitable for the experiment of "like charges repel each other"
(2) Take a plexiglass and a plastic toothbrush handle and drill a small hole in the center of each L button (don't drill it through). Then find a piece of plexiglass (transparent plastic, rubber stopper or square eraser) as the base, heat the needle and insert it into the base. Then put the plexiglass with small holes and the toothbrush handle on the tip of the needle, let them keep balance and rotate flexibly, and then demonstrate the experiment of "the same kind of electricity repels and the different kinds of electricity attract"
(3) Find a section of copper wire, iron wire or aluminum wire with the length of 1.som, round both ends, remove the insulation, and make the knife edge into the shape of figure 1. It would be better if the joint of the ring can be welded firmly or a small ball can be welded on the ring. Find another piece of aluminum foil paper in the cigarette case, wet it with water and lay it flat on the glass plate, and wipe off the paper on the back. Then cut 3-4.
An aluminum foil strip with a length of cm and a width of 0.scm is folded in half and then embedded with copper.