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⚛️ Physics  ·  Units and Measurements  ·  NEET & JEE

A screw gauge has pitch 1 mm and 100 circular divisions. While measuring a wire, the main scale reads 4 mm and the 30th circular division coincides. If it has a negative zero error of 5 divisions, the corrected diameter is:

Answer: 4.35 mm.

  • A 4.25 mm
  • B 4.30 mm
  • C 4.35 mm
  • D 4.80 mm

Correct answer: C. 4.35 mm

Explanation: Least count = 0.01 mm; observed = 4.30 mm; corrected = observed − zero error = 4.30 − (−0.05) = 4.35 mm.

The 7 SI Base UnitsLengthmetre (m)fundamentalMasskilogram (kg)Timesecond (s)Electric Currentampere (A)Temperaturekelvin (K)Amount ofSubstancemole (mol)LuminousIntensitycandela (cd)Every other physical quantity is derived by combining powers of these 7 base units

The 7 SI base units. All derived units (newton, joule, watt, volt, etc.) can be expressed as combinations of these 7 fundamental units raised to various powers.

Concept context

SI base units, dimensional analysis, significant figures, and error propagation. The toolkit every physics calculation relies on.

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