What is the proper procedure to measure current in a specific portion of a circuit?

• A. Switch off power, break the circuit, insert ammeter in series, then restore power.
• B. Energize the circuit and place ammeter across the component.
• C. Connect ammeter in parallel around the component.
• D. Calculate current from voltage and resistance.

Answer: (A)

To measure current in a specific portion of a circuit, you must insert the ammeter in series with that portion so the same current flows through the meter. The proper procedure is to power down the circuit, break the connection at the point where you want to measure, place the ammeter in line with the circuit path, and then restore power to read the current. This works because current in a series path is the same through every element, so the meter will accurately reflect the actual current in that segment. Placing the meter in parallel would not measure current and can create a short or bypass the component, which is not how current is measured. Measuring current by calculating from voltage and resistance is not a direct measurement and relies on known values and assumptions; you’re not obtaining the actual current in real time through the circuit.