Which unit is used to measure electrical current?

• A. Amperes
• B. Ohms
• C. Volts
• D. Watts

Answer: (A)

Electrical current is the rate at which electric charges flow through a conductor. The unit used to measure that flow is the ampere (A). An ampere means one coulomb of charge passes a point each second. This is different from voltage, which is the potential difference measured in volts, and from resistance, which is the opposition to current measured in ohms, as well as from power, the rate of energy transfer measured in watts. Ohm’s law ties these together: current equals voltage divided by resistance, so increasing voltage or decreasing resistance increases current, all expressed in amperes.