The magnitude of the charge on a single proton or electron is called the elementary charge, e . Similar electric charges repel each other.
Charged objects attract some neutral objects.
An electric current is the rate of flow of charge passing through a cross-sectional area in a conductor. It is considered to be a flow of positive charges. An ammeter is used to measure current in an electric circuit. It must be connected in series with the circuit. It must have a low internal resistance.