Question

Figure shows the position of vernier scale while measuring the external length of a wooden cylinder.

1. What is the length recorded by the main scale?
   
2. Which reading of vernier scale coincides with the main scale?
3. Calculate the length.

Answer 1

Main scale divisions of vernier callipers in one centimetre = 10

Pitch = `"Unit of main scale"/"Number of divisions in the unit"`

= `1/10` cm = 0.1 cm

Least count = `"Pitch"/"No. of divisions on the vernier scale"`

L.C. = `0.1/10` cm = 0.01 cm

1. Length recorded by main scale = 10.2 cm
⇒ Main scale reading is 10.2 cm

2. Reading of vernier scale coinciding with main scale = 7th
⇒ Vernier scale division (V.S.D.) is 7th

3. Length recorded by vernier callipers
= Main scale reading + L.C. × V.S.D.
= 10.2 + 0.01 × 7
= 10.2 + 0.07
= 10.27 cm