All other charges are multiples of this basic unit of charge. Electric field is a vector, i.e. it has both magnitude and direction. The unit is volt . One volt is one joule per coulomb. A conductor allows electrons to pass with little loss of energy.
Examples are metals, such as copper.
An insulator does not allow electrons to pass through. Examples are plastics. The unit is ampere, which is coulomb per second. Electric current can be produced by a chemical reaction, such as in a battery or with a mechanical generator. A typical frequency f in household current is 60 cycles per second, or 60 Hz.