NEET Physics
NEETPhysicsExperimental SkillsClass 12

What does “Least count and instrument reading” actually mean in Experimental Skills, and why does it matter for NEET?

An instrument cannot honestly resolve changes smaller than its least count. A final reading combines the main-scale reading, coinciding-division contribution, and the zero-error correction with correct sign.

In simple words: An instrument cannot honestly resolve changes smaller than its least count. A final reading combines the main-scale reading, coinciding-division contribution, and the zero-error correction with correct sign. Getting Least count and instrument reading clear matters because NEET questions on Experimental Skills usually test this idea directly, not just a formula you memorised.

Key point

Least count and instrument reading

Common mistake

adding a positive zero error instead of subtracting it from the observed reading.

Memory tip

correct reading = observed reading - zero error.

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