Question

Consider the following data: 10 main scale division = 1cm, ${10}^{th}$ vernier division match with $9^{th}$ Main scale division. While measuring the zero error of the vernier we see that zero of vernier scale is to the right of the zero marking of the main scale with $6^{th}$ vernier division coinciding with main scale divisions. The actual reading for length measurement is 4.3 cm with 2nd vernier division coinciding with main scale graduation. Estimate the length.

• A. 4.32 cm
• B. 4.38 cm
• C. 4.26 cm
• D. none of these

Answer 1

The correct option is C

4.26 cm

10 MSD = 1 cm

1 MSD = $\frac{1}{10}$cm = 1 mm

Also 10 VSD = 9 MSD

1 VSD = $\frac{9}{10}$MSD

1 VSD = 0.9mm

least count of vernier Calliper

L.C. = 1 MSD - 1 VSD = 1 mm - 0.9mm = 0.1 mm

Also given, while measuring Zero error zero of vernier is to right of main scale so when the scale should have read 0 it was actually reading 0+6 LC

Zero error = 6$\times$0.1 = 0.6mm

Correction = -0.6mm

Given reading = $(4.3+2\times 0.01-0.06)$cm

= 4.26 cm