There was a section of my textbook that mentions this and I can't understand it...
Q: Is static electricity caused by friction?
A: No. It appears when two dissimilar insulating materials are placed into intimate contact and then separated, they get charged and all that is required is touching. It is only that the process of rubbing one material upon another can greatly increase the surface area.
I can't understand the answer. What does dissimilar mean here? Does it refer to different magnitudes of charge? If both the objects are electrically neutral and come in contact, how can they charge each other?