An electronics technician is preparing a digital multimeter to take several operational me… — Armed Services Vocational Aptitude Battery (ASVAB)

An electronics technician is preparing a digital multimeter to take several operational measurements across an electro-mechanical control assembly. Match each specific measurement task on the left with its correct meter configuration and circuit placement on the right.

Measuring line potential across an energized $120\text{ V AC}$ blower motor circuitConnect test leads in parallel across the load; red lead in $\text{V}/\Omega$ jack, black in $\text{COM}$ ; rotary switch set to $\text{ACV}$ (high input impedance)
Measuring an expected $7.5\text{ A}$ continuous direct current drawn by a fuel pumpBreak circuit and connect in series; red lead in unfused/high-current $\text{10A}$ jack, black in $\text{COM}$ ; rotary switch set to $\text{DCA}$ (low internal shunt resistance)
Measuring a low-level $35\text{ mA}$ control loop current in a $24\text{ V DC}$ sensor lineBreak circuit and connect in series; red lead in fused $\text{mA}/\mu\text{A}$ jack, black in $\text{COM}$ ; rotary switch set to $\text{DCA}$ (low internal resistance)
Measuring the direct-current voltage drop across an active $5\text{ V}$ microcontroller pull-up resistorConnect test leads in parallel across the component; red lead in $\text{V}/\Omega$ jack, black in $\text{COM}$ ; rotary switch set to $\text{DCV}$ (high input impedance)

Answer

1 matches with AC voltage parallel setup (

\text{ACV}

\text{V}/\Omega

jack); 2 matches with high-current DC series setup (

\text{DCA}

\text{10A}

jack); 3 matches with low-current DC series setup (

\text{DCA}

\text{mA}/\mu\text{A}

jack); 4 matches with DC voltage parallel setup (

\text{DCV}

\text{V}/\Omega

jack).

Each multimeter measurement demands a specific combination of circuit topology, dial mode, and terminal jack. Voltage measurements are always taken in parallel across points of potential difference using the high-impedance

\text{V}/\Omega

jack, selecting

\text{ACV}

for AC line power and

\text{DCV}

for steady logic signals. Current measurements require breaking the circuit and inserting the meter in series; currents exceeding typical milliamp thresholds require the heavy-duty

\text{10A}

terminal, whereas sub-ampere currents use the high-resolution

\text{mA}/\mu\text{A}

terminal.

Step-by-Step Solution

Differentiate between voltage and current measurement topologies

Voltage measurements must always be connected in parallel with high internal meter impedance to avoid loading the circuit; current measurements must be inserted in series with low internal shunt resistance so all current passes through the meter.

An ammeter placed in parallel creates a short circuit, while a voltmeter placed in series blocks normal circuit current.

Distinguish between AC and DC measurement modes

The

120\text{ V}

utility line requires

\text{ACV}

, whereas the

5\text{ V}

logic drop requires

\text{DCV}

Selecting the incorrect waveform mode results in inaccurate readings or zero measured potential.

Select appropriate current input jacks based on magnitude

7.5\text{ A}

demands the dedicated high-current

\text{10A}

jack to prevent blowing the internal milliamp fuse, whereas

35\text{ mA}

utilizes the fused

\text{mA}/\mu\text{A}

input jack for optimal resolution.

Currents exceeding milliamp scale ratings will immediately trip the meter's internal protective fuse if connected to the

\text{mA}

terminal.

Key Concept

Multimeter Configuration, Jack Selection, and Circuit Placement Principles

Estimated Time:1m 15s

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Key Concept

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