In the teaching of electricity in the third grade, many teachers used to ask students such a question in order to introduce the teaching of "like charges repel and opposite charges attract": "When a rubber rod rubbing fur is close to a light object, it will be seen that the light object is attracted first and then bounced off quickly. Why "? For this question, the questioner's expected answer is: "The rubbing glue stick is a charged body, which can attract light and small objects. When light and small objects come into contact with the glue stick, they will have the same charge as the glue stick and bounce off quickly because of the repulsion of the same charge. " At first glance, there seems to be nothing wrong with this question and answer, but comparing the test results with the experimental results, we find that the experimental results are quite different from the test scenarios! I have been doing experiments when charged objects are close to light and small objects (whether light and small objects are conductors or insulators) in many years of teaching. The observed phenomena are: after light and small objects are attracted by charged objects, some light and small objects are adsorbed on the charged objects, and some light and small objects are excluded from the charged objects; However, after being pulled away from the charged body for a certain distance, the adsorbed light and small objects are repelled and far away from the charged body. When an object comes into contact with a charged body, it will have the same electrical properties as the charged body. Why do you sometimes leave the charged body because of the repulsion of the same charge, but you are still attracted to the charged body with the same electrical property?