Question

One 8cm on the main scale of the vernier callipers is divided into 10 equal parts. If the 10 divisions of the vernier coincide with the small divisions the main scale, the least 10 divisions of the callipers is
A. 0.005 cm
B. 0.002 cm
C. 0.01 cm
D. 0.05 cm

Answer 1

Hint: Vernier callipers measure components very accurately for thin instruments such as tubes, and it has fixed main scale moving over a vernier scale. Vernier callipers scores well over individual rollers.

Complete step by step answer:
Least count is given by:
$LC = 1MSD - 1VSD$…… (I)
Here LC is the least count, MSD is the vernier scale division and VSD is the vernier scale division.
Here
$
  10\,VSD = 9\,MSD \\
  1\,VSD = 0.9\,MSD \\
 $
Substituting $1\,VSD = 0.9\,MSD$ in equation (I), it comes out to be:
$
  LC = 1\,MSD - 0.9\,MSD \\
  LC = 0.1\,MSD......({\text{II)}} \\
 $
Assume $1\,MSD = 1\,{\text{mm}}$ and substituting in equation (II), it gives.
$
  LC = 0.1\,{\text{mm}} \\
  LC = 0.01\,{\text{cm}} \\
 $

Additional information: Vernier callipers is a visual help to take reading between two scales or two graduation scales thereby increasing the resolution and finding the error by mechanical interpolation and using vernier acuity to remove human error measurement.

Note: Vernier callipers measure length, breadth, height, depth, diameter of thin components which cannot be measured by an ordinary instrument and which cannot be seen by naked eye.