Question

The side of a cube is measured by a vernier caliper (10 divisions of a vernier scale coincide with 9 divisions of main scale, where 1 division of main scale is 1 mm). The main scale reads 10 mm and first division of vernier scale coincides with the main scale. Mass of the cube is 2.736g. Find the density of the cube in appropriate significant figures.

[IIT JEE 2005]

• A. $2.6g/c{m}^3$
• B. $2.655g/c{m}^3$
• C. $2.65g/c{m}^3$
• D. None of these

Answer 1

The correct option is B

$2.655g/c{m}^3$

least count of vernier caliper = $\frac{1MSD}{\text{Number of VSD}}$ = $\frac{1}{10}$ = 0.1mm

$\therefore$Side of cube =10mm + 1$\times$ 0.1mm = 1.01cm

Density = $\frac{2.736}{(1.01{)}^{3}c{m}^3}$ = 2.66 $g/c{m}^3$

Correct to 3 significant figures.