An ammeter is used to measure what in a circuit?

• A. Voltage across a component
• B. Resistance of a circuit
• C. Power consumption
• D. The amount of electron flow in amperes

Answer: (D)

Current is the rate at which electric charges flow through a circuit, and an ammeter is built to measure that flow. It reads in amperes, so it captures how much electron flow passes a point per second. To get an accurate reading without disturbing the circuit, the ammeter is placed in series with the components, and it has very low resistance to minimize any voltage drop. By contrast, devices that measure voltage are connected in parallel and have high resistance, and devices that measure resistance are typically used to determine how much resistance a component offers. If you need power, you multiply current by voltage, rather than reading power directly from the ammeter. So the ammeter’s job is to quantify the current—the amount of electron flow—expressed in amperes.