An electronics technician is testing various circuits under operating conditions. Which mu… — Armed Services Vocational Aptitude Battery (ASVAB)

An electronics technician is testing various circuits under operating conditions. Which multimeter dial setting, input jack configuration, and connection method on the right correctly matches each measurement task on the left?

Measuring direct current ( $8\text{ A}$ ) supplied to an active $12\text{ V}$ automotive cooling fanRed lead in $10\text{ A}$ jack, dial set to $\text{DC A}$ , meter inserted in series with the opened power line
Measuring line potential difference across an energized $120\text{ V}$ alternating-current line filterRed lead in $\text{V}/\Omega$ jack, dial set to $\text{AC V}$ , meter connected in parallel across the line terminals
Measuring low direct current ( $15\text{ mA}$ ) passing through a sensor reference circuitRed lead in $\text{mA}/\mu\text{A}$ jack, dial set to $\text{DC A}$ , meter inserted in series with the opened signal line
Measuring steady direct-current voltage drop across an operational $24\text{ V}$ solenoid coilRed lead in $\text{V}/\Omega$ jack, dial set to $\text{DC V}$ , meter connected in parallel across the solenoid terminals

Answer

1. High DC current (

8\text{ A}

) matches red lead in

10\text{ A}

jack,

\text{DC A}

dial, connected in series. 2. AC line voltage (

120\text{ V AC}

) matches red lead in

\text{V}/\Omega

jack,

\text{AC V}

dial, connected in parallel. 3. Low DC current (

15\text{ mA}

) matches red lead in

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

jack,

\text{DC A}

dial, connected in series. 4. DC voltage drop (

24\text{ V DC}

) matches red lead in

\text{V}/\Omega

jack,

\text{DC V}

dial, connected in parallel.

Each multimeter measurement requires three matching conditions: correct input jack, matching dial mode (AC/DC and quantity), and proper circuit hookup. For high direct current (

8\text{ A}

), the red probe must occupy the

10\text{ A}

jack and be inserted in series with the cooling fan. For alternating voltage (

120\text{ V AC}

), the red probe must occupy the

\text{V}/\Omega

jack, dial set to

\text{AC V}

, connected in parallel across the filter. For low direct current (

15\text{ mA}

), the red probe must be in the

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

jack and inserted in series. For direct voltage (

24\text{ V DC}

), the red probe uses the

\text{V}/\Omega

jack, dial set to

\text{DC V}

, connected in parallel across the solenoid.

Step-by-Step Solution

Differentiate between voltage and current measurement topologies

Voltmeters have high internal impedance and must be connected in parallel across components; ammeters have very low internal resistance and must be connected in series by breaking the circuit path.

Connecting an ammeter in parallel creates a short circuit, while placing a voltmeter in series creates an unintended open/high resistance in the branch.

Determine input jack and dial settings for current measurements based on expected amperage magnitude

The

8\text{ A}

fan draw exceeds standard milliampere fuses (

200\text{--}400\text{ mA}

), requiring the unfused or heavy-fused

10\text{ A}

jack and

\text{DC A}

mode. The

15\text{ mA}

sensor signal fits within the high-resolution

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

jack and

\text{DC A}

mode.

Overloading low-current input jacks blows the meter's internal protective fuse.

Determine input jack and dial settings for voltage measurements based on waveform type

The

120\text{ V}

alternating-current line filter requires the

\text{V}/\Omega

jack and

\text{AC V}

function. The

24\text{ V}

DC solenoid drop requires the

\text{V}/\Omega

jack and

\text{DC V}

function.

Both voltage measurements utilize the high-impedance

\text{V}/\Omega

jack connected in parallel across the component, but the selector dial must match the signal's electrical nature (AC vs. DC).

Key Concept

Multimeter Configuration for Voltage and Current Measurements

Estimated Time:1m 15s

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Key Concept

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