Your friend has been learning how to charge objects with fri…
Your friend has been learning how to charge objects with friction in her lab. She has a set of plastic rods and charges some of them with silk, some others with fur, and some are left uncharged. She then gives you a plastic rod but doesn’t tell you what material she used to charge it or whether that rod was charged at all. You decide to bring the plastic rod close to a gold leaf electroscope. The electroscope initially carries an excess positive charge. As the rod is moved near the electroscope you observe that the leaves of the electroscope collapse together. What do you conclude?
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