Final answer:
Electric current is the rate of charge flow through a circuit, measured in amperes (A), defined as one coulomb per second. A large current moves more charge in less time, whereas a small current moves less charge more slowly. Direct current (DC) refers to continuous flow in a single direction.
Step-by-step explanation:
Electric current is the term that describes the rate at which electric charge moves through a circuit. This flow is usually due to the movement of electrons in the external circuit. When there is a large current, for example, that which is used to run a refrigerator, a substantial amount of charge moves in a short amount of time. Conversely, a small current, like that which powers a calculator, results in a smaller flow of charge over a longer duration.
The SI unit of current is the ampere (A), which is defined as one coulomb (C) of charge passing a fixed point in the circuit per second. This definition underscores that current is purely about the flow rate of charge, regardless of the medium through which the charge is moving. It might be electrons flowing through wires or ions moving in an electrolyte. In formal terms, if a constant current, I, flows through a conductor for a time interval, t, the total charge transferred is given by the product Q = It.
Direct current (DC) is a type of electric current where charge flows only in one direction. Such continuity in the flow direction is typical of batteries and DC power supplies.