When diagnosing electrical circuits with a digital multimeter (DMM) set to measure resista… — Armed Services Vocational Aptitude Battery (ASVAB)

When diagnosing electrical circuits with a digital multimeter (DMM) set to measure resistance ( $\Omega$ ) or continuity, different display readings indicate specific circuit and component conditions. Match each multimeter reading to its corresponding electrical condition:

Display shows $0.0\ \Omega$ with a steady audible beep across a closed single-pole switchContinuous, unbroken path confirming a properly functioning closed contact
Display reads $\text{OL}$ (over-limit/infinite resistance) across a heating element rated for $24\ \Omega$ Internal open circuit indicating a burned or broken heating element
Display indicates $4.7\ \text{k}\Omega$ across an isolated yellow-violet-red resistorComponent exhibits normal resistance conforming to its nominal design rating
Display shows rapidly fluctuating values and illuminates an active voltage warning indicatorFailure to de-energize the circuit before taking resistance measurements

Cevap

The closed switch reading of

0.0\ \Omega

with a beep matches a continuous unbroken path; the

\text{OL}

reading on a

24\ \Omega

element matches an internal open circuit; the

4.7\ \text{k}\Omega

reading matches normal component resistance; and fluctuating readings with a voltage warning match measuring resistance on an energized circuit.

Each pair directly aligns the meter display with fundamental circuit states:

0.0\ \Omega

with a beep indicates unbroken continuity;

\text{OL}

on a load component signifies an open-circuit failure; a reading matching component ratings indicates proper health; and erratic values with a voltage warning indicate power was improperly left connected.

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Evaluate the zero-ohm reading with an audible tone

Identifies full continuity (closed path)

Multimeters use continuity mode to verify a continuous electrical path; zero ohms represents negligible resistance across closed switch contacts.

Evaluate the infinite resistance (OL) reading on a load component

Identifies an open circuit condition

A healthy

24\ \Omega

heating element should read approximately

24\ \Omega

; an OL reading indicates the internal filament or element wire is completely severed.

Evaluate the

4.7\ \text{k}\Omega

reading against the resistor color bands

Identifies normal nominal operation

Yellow (

4

), violet (

7

), and red multiplier (

10^2 = 100

) equals

4700\ \Omega

4.7\ \text{k}\Omega

, matching the measured reading.

Evaluate erratic values accompanied by a meter voltage warning

Identifies a live-circuit testing safety violation

Resistance must always be measured on fully de-energized circuits. Live current backfeeding into the meter distorts the internal test current and triggers warnings.

Anahtar Kavram

Interpreting digital multimeter resistance and continuity readings under open, closed, nominal, and live-circuit conditions

Tahmini Süre:1m 15s

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