In current measurement, what is the proper placement of the meter?

• A. In parallel with the circuit
• B. Across a resistor
• C. In series with the circuit
• D. Across the power supply

Answer: (C)

To measure current, you insert the meter in series with the circuit so that all the current flowing through the load also flows through the meter. This is why ammeters are designed with very low internal resistance, minimizing any voltage drop and disturbance to the circuit. If you place the meter in parallel with the circuit, it would create an alternate path for current, often drawing most of the current because the meter’s resistance is much lower than the load, which leads to an inaccurate reading or even a short. Similarly, placing it across a resistor or across the power supply would bypass parts of the circuit or cause a short, not measure the actual current through the intended path. So the correct placement is in series with the circuit.