What does “Least count” actually mean in Units, Dimensions & Measurement, and why does it matter for JEE?
the smallest value an instrument can reliably read — e.g. 0.01 mm for a screw gauge.
In simple words: the smallest value an instrument can reliably read — e.g. 0.01 mm for a screw gauge. Getting Least count clear matters because JEE questions on Units, Dimensions & Measurement usually test this idea directly, not just a formula you memorised.
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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