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Zorluk: Çok zorMultimeter: Resistance and Continuity

An electronics technician is troubleshooting a complex, completely de-energized control panel. Match each component testing scenario using a digital multimeter (DMM) to its expected meter reading and diagnostic meaning.

  • Measuring across an intact, solid length of copper wire using the continuity setting.Displays 0.0 Ω0.0\ \Omega (or near zero) and emits a continuous audible beep.
  • Testing a known good 10 kΩ10\ \text{k}\Omega resistor that is still soldered in parallel with a 2.5 kΩ2.5\ \text{k}\Omega resistor on the board.Displays approximately 2 kΩ2\ \text{k}\Omega due to the alternative circuit path.
  • Measuring a functional DC relay coil that has been completely isolated from the rest of the circuit.Displays a specific, steady nominal resistance (e.g., 75 Ω75\ \Omega) representing intact wire windings.
  • Checking a removed, blown ceramic cartridge fuse using the resistance setting.Displays "OL" or "1.", indicating infinite resistance and an open circuit.

Cevap

Intact wire matches to 0.0 ohms and a beep; the in-circuit 10k resistor matches to 2k ohms due to parallel paths; the isolated relay coil matches to a specific nominal resistance; and the blown fuse matches to OL (infinite resistance).
Each scenario accurately reflects standard DMM behavior. Intact wires show continuity (0 ohms/beep). Components measured in-circuit show parallel equivalent resistance (2 kΩ2\ \text{k}\Omega for a 10k and 2.5k parallel combination). Relay coils have measurable nominal resistance, and blown fuses read as open circuits (OL).

Adım Adım Çözüm

1
Analyze the intact copper wire scenario.
Matches to 'Displays 0.0 ohms and emits a continuous beep'.
A solid wire has negligible resistance, representing a perfect short or closed circuit.
2
Evaluate the in-circuit resistor measurement.
Matches to 'Displays approximately 2 kOhms'.
The DMM measures the total equivalent resistance of the parallel circuit path. Using the formula Req=R1×R2R1+R2R_{eq} = \frac{R_1 \times R_2}{R_1 + R_2}, the result is 10×2.510+2.5=2 kΩ\frac{10 \times 2.5}{10 + 2.5} = 2\ \text{k}\Omega.
3
Determine the reading for an isolated, functional relay coil.
Matches to 'Displays a specific, steady nominal resistance'.
Relay coils are made of thin wire wound many times, which inherently possesses a measurable nominal resistance (unlike a dead short).
4
Identify the reading for a blown fuse.
Matches to 'Displays OL or 1.'.
A blown fuse breaks the circuit path, resulting in infinite resistance (an open circuit).

Anahtar Kavram

Digital Multimeter Resistance and Continuity Interpretation
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Konular

Multimeter: Resistance and Continuity

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