Least Count Of Screw Gauge — the NEET Physics formula with its derivation, variables, validity constraints and worked solver.
Least Count of Screw Gauge The formula is applicable to any standard screw gauge instrument for measuring small lengths (e.g., diameter of thin wires, thickness of sheets) with high precision. Definition of Pitch (P): Linear distance moved by the screw for one complete rotation of the circular scale. Let N be the total number of divisions on the circular scale. The least count (LC) represents the linear distance moved when the circular scale is rotated by exactly one division. Therefore, LC = P / N. Assumes the screw gauge has a uniform pitch. The instrument must not be damaged such that the circular scale movement is linearly related to linear displacement. Confusing Main Scale Reading (MSR) with Pitch. Assuming N is the observed reading instead of the total number of divisions. Neglecting to convert units (e.g., mm to cm) when calculating least count for a problem. Confusing Least Count with Zero Error.