I keep getting “Least count” questions wrong in Units, Dimensions & Measurement. What's the trap?
forgetting the zero-error correction of a vernier or screw gauge.
The usual trap: forgetting the zero-error correction of a vernier or screw gauge. How to avoid it: always note and subtract the zero error before recording a reading. Go back to the definition — the smallest value an instrument can reliably read — e.g. 0.01 mm for a screw gauge.
Key point
Least count
Common mistake
forgetting the zero-error correction of a vernier or screw gauge.
Memory tip
always note and subtract the zero error before recording a reading.
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