Answer the following question given this paragraph: 

An electroscope is a device used to study charge. When a positively charged object (the rod) nears the upper post, electrons flow to the top of the jar leaving the two gold leaves postivley charged. The leaves repel each other since both hold postive, like charges. The VSEPR theory says that electron pairs, also a set of like charges, will repel each other such that the shape of the molecule will adjust so that the valence electron-pairs stay as far apart from each other as possible.


Q: What device is used to study charge?


A:
electroscope