What is current?

• A. The energy per unit charge
• B. The amount of charge in a circuit
• C. The rate of flow of charge
• D. The opposition to the flow of electrons

Answer: (C)

Current is the rate at which electric charge flows. It is measured in amperes, defined as one coulomb passing a point each second. So if 3 coulombs move past a point in 2 seconds, the current is 1.5 amperes. This emphasizes flow over time, not the total amount of charge stored in the circuit. By contrast, energy per unit charge is voltage (potential difference), the amount of charge in the circuit is just total charge, and the opposition to flow is resistance. In conductors, electrons carry charge, but the magnitude of current is defined by how much charge crosses a point per unit time, regardless of which direction the charges move.