Why, when electrified by friction, equal in absolute value, but opposite in sign, charges appear on bodies?

During electrification, the charges of the bodies are equal, because the number of electrons leaving the body was compensated by the number of protons. Therefore, the charges are equal in magnitude. The predominance of protons in an atom leads to the formation of a positive charge of one of the atoms, and the predominance of electrons in a contacting atom leads to the formation of a negative charge.

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