When using a multimeter to measure current, why must the meter be placed in series with the load?

When using a multimeter to measure current, why must the meter be placed in series with the load?

• A. To bypass the load for faster measurement.
• B. Because current is measured by passing the circuit through the meter.
• C. To measure the voltage across the load.
• D. To prevent the meter from heating up.

Answer: (B)

Measuring current requires the same amount of current to flow through the measuring device as through the load, so the meter must be placed in series with the load. A current-measuring mode uses a very low-value internal shunt resistance and reads the voltage drop across that shunt to determine the current. When the meter is inserted in series, all the current in that branch passes through both the load and the meter, giving an accurate reading of the load current. If the meter were placed in parallel, it would present a path of much lower resistance than the load, causing most of the current to bypass the load. This shunts the circuit, can blow fuses or damage the meter, and the measurement would not reflect the load’s actual current. In contrast, measuring voltage is done in parallel, which is why current measurement specifically requires a series connection.

Measuring current requires the same amount of current to flow through the measuring device as through the load, so the meter must be placed in series with the load. A current-measuring mode uses a very low-value internal shunt resistance and reads the voltage drop across that shunt to determine the current. When the meter is inserted in series, all the current in that branch passes through both the load and the meter, giving an accurate reading of the load current.

If the meter were placed in parallel, it would present a path of much lower resistance than the load, causing most of the current to bypass the load. This shunts the circuit, can blow fuses or damage the meter, and the measurement would not reflect the load’s actual current. In contrast, measuring voltage is done in parallel, which is why current measurement specifically requires a series connection.