Physics · Units And Measurements · NEET
They are the same value. 0.1 mm = 0.01 cm. Both are correct. In NEET options, watch the unit carefully: if choices are in cm, write 0.01 cm; if in mm, write 0.1 mm. A common trap is picking the same number but the wrong unit.
MSD = Main Scale Division, the smallest gap printed on the fixed main scale (usually 1 mm). VSD = Vernier Scale Division, one gap on the sliding vernier scale. In a standard caliper, 10 VSD are made to fit inside 9 MSD, so 1 VSD = 0.9 mm. The formula LC = 1 MSD − 1 VSD = 1 − 0.9 = 0.1 mm follows directly.
Three steps. (1) Main Scale Reading (MSR): read the main scale mark just before the vernier zero. (2) Vernier Scale Reading (VSR): find the vernier line that exactly lines up with any main scale line; that division number is your VSR. (3) Total = MSR + (VSR x LC). Example: MSR = 5.0 cm, coinciding division = 8, LC = 0.01 cm gives 5.0 + 0.08 = 5.08 cm (before any zero-error correction).
n VSD = (n-1) MSD means 1 VSD = (n-1)/n MSD. So LC = 1 MSD − 1 VSD = [1 − (n-1)/n] MSD = (1/n) MSD. If the main scale has n divisions per cm, then 1 MSD = 1/n cm, giving LC = 1/n^2 cm. This exact result was asked in NEET 2019.
No. Zero error is a fixed shift you add or subtract at the end; it does not change the LC. LC depends only on the scale design (MSD and VSD). First read MSR + VSR x LC, then correct for zero error: corrected reading = observed reading − zero error.
The main scale of a vernier calliper has n divisions/cm. n divisions of the vernier scale coincide with (n-1) divisions of the main scale. The least count of the vernier calliper is:
In a vernier callipers, (N+1) divisions of the vernier scale coincide with N divisions of the main scale. If 1 MSD represents 0.1 mm, the vernier constant (in cm) is:
The diameter of a spherical object is measured with a vernier caliper whose 10 vernier scale divisions (VSD) equal 9 main scale divisions (MSD). One MSD is 0.1 cm and the zero of the vernier scale is at x = 0.1 cm when the jaws are closed. If the main scale reading is M = 5 cm and the coinciding vernier division is 8, the measured diameter after zero-error correction is:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
0.1 mm, which equals 0.01 cm. It comes from LC = 1 MSD − 1 VSD, where 10 vernier divisions fit into 9 mm of the main scale.
LC = value of 1 main scale division − value of 1 vernier scale division = 1 MSD − 1 VSD. Equivalently, LC = (smallest main scale division) / (number of vernier divisions).
A vernier caliper uses a sliding vernier scale and typically has LC = 0.01 cm. A screw gauge uses a rotating circular scale with pitch, giving a smaller LC = pitch / number of circular divisions, usually 0.001 cm, so it is more precise for very thin objects.
Vernier constant is just another name for the least count of a vernier caliper. Both mean the smallest length the instrument can read.
Read the closed-jaw value first. If the vernier zero is to the right of the main scale zero, it is a positive zero error (subtract it); if to the left, it is negative (add it). Correct reading = observed reading − zero error.
