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Difficulty: EasyMeasurement of Length and Measuring Instruments

A micrometer screw gauge with a positive zero error of +0.04 mm+0.04\text{ mm} gives an observed reading of 2.46 mm2.46\text{ mm} when measuring the diameter of a thin wire. What is the actual diameter of the wire?

  1. 2.42 mm2.42\text{ mm}Answer
  2. B
    2.46 mm2.46\text{ mm}
  3. C
    2.50 mm2.50\text{ mm}
  4. D
    2.38 mm2.38\text{ mm}

Answer

The actual diameter of the wire is 2.42 mm2.42\text{ mm}.
To calculate the actual reading on a measuring instrument, use the relationship Actual Reading=Observed Reading−Zero Error\text{Actual Reading} = \text{Observed Reading} - \text{Zero Error}. Subtracting +0.04 mm+0.04\text{ mm} from 2.46 mm2.46\text{ mm} yields 2.42 mm2.42\text{ mm}.

Step-by-Step Solution

1
Identify the given readings
Observed reading = 2.46 mm2.46\text{ mm}, Zero error = +0.04 mm+0.04\text{ mm}
Extract values needed for zero error correction.
2
Apply zero error correction formula
Actual Reading=Observed Reading−Zero Error=2.46 mm−(+0.04 mm)=2.42 mm\text{Actual Reading} = \text{Observed Reading} - \text{Zero Error} = 2.46\text{ mm} - (+0.04\text{ mm}) = 2.42\text{ mm}
A positive zero error means the instrument reads higher than true zero, so the zero error must be subtracted from the observed reading.

Key Concept

Instrument Zero Error Correction
Estimated Time:45s
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Topics

Measurement of Length and Measuring Instruments

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