A direct vernier with 1 MSD = 1 mm has the same least count as a screw gauge of pitch 0.4 mm and 80 circular divisions. If the vernier relation is N VSD = (N − 2) MSD, find N.
Physics · Unit dimension and error · vernier callipers and screw gauge
JEE Mains NEET

Question

A direct vernier with 1 MSD = 1 mm has the same least count as a screw gauge of pitch 0.4 mm and 80 circular divisions. If the vernier relation is N VSD = (N − 2) MSD, find N.

G1 Physics · Accepted Answer

Screw-gauge LC = 0.4/80 = 0.005 mm. Vernier LC = 2/N mm. Hence 2/N = 0.005, so N = 400.