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Difficulty: EasyMultimeter: Resistance and Continuity

An electronic technician needs to measure the resistance of a resistor installed on a circuit board to verify its value. What is the correct sequence of steps to safely and accurately perform this measurement?

  1. 1Disconnect all power sources from the circuit to ensure the board is completely de-energized.
  2. 2Disconnect or desolder at least one lead of the resistor to isolate it from the rest of the circuit.
  3. 3Set the digital multimeter selector dial to the resistance (Ω\Omega) measurement mode.
  4. 4Firmly touch the multimeter test probes across the terminals of the resistor and read the value on the display.

Answer

Disconnect power to the circuit →\rightarrow Isolate at least one lead of the resistor →\rightarrow Set the multimeter dial to resistance (Ω\Omega) →\rightarrow Place the test probes across the component leads and observe the display.
The correct sequence begins with de-energizing the circuit for safety and instrument protection, isolating at least one lead to eliminate parallel circuit paths, configuring the multimeter to the Ohms function, and finally contacting the leads across the component to observe the reading.

Step-by-Step Solution

1
Ensure all power to the circuit is disconnected.
The circuit is completely de-energized and safe to work on.
Multimeters measure resistance by supplying their own small internal voltage; external power will damage the meter and produce invalid readings.
2
Lift or disconnect at least one lead of the resistor from the circuit board.
The resistor is isolated from other components.
Parallel paths in the circuit network would provide alternative current loops, causing the meter to read lower than the true component value.
3
Turn the rotary switch on the multimeter to the resistance (Ω\Omega) range.
The multimeter is configured in ohmmeter mode.
The meter must be in the correct mode before probes are applied to the device under test.
4
Connect the black and red test leads across the resistor terminals.
The resistance value appears on the digital readout.
The meter sends a small internal current through the component, measures the resulting voltage drop, and displays the calculated resistance.

Key Concept

Safely and accurately measuring component resistance requires de-energizing the circuit, isolating the component from parallel paths, selecting the Ohms mode, and applying the test probes.
Estimated Time:45s
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Topics

Multimeter: Resistance and Continuity

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