Question #b040e
1 Answer
That has been established through experiment.
Explanation:
"Positively charged" and "negatively charged" are arbitrary labels which describe how a particle behaves under certain conditions, for example when put in an Electric field. Now you may say the electric field is also established through charges making this argument circulatory, but keep in mind that the electric field is nothing but a modern establishment of the ancient experience of the rod and fur (see link below). The thing is just that people observed a certain kind of behavior of materials when rubbed with fur (in this case) such as attraction and repulsion. To describe these phenomena in terms suitable for practical use they named them positive and negative charges. But they also could've labeled them sun and moon, for positive and negative is as arbitrary as it gets, but as many names in engineering, are, one could argue, best for practical use.
