# How to measure with vernier calipers

With the vernier calipers we can measure the thickness of glass plates,metal sheets,lengths of objects like cylinders,tubes.We can also measure the external and internal diameters of the tubes and rings.We can also measure the depth of tubes and the water level in a jar.

Description of Vernier Calipers: A Vernier calipers consists of mainly two parts i) A 2cm wide 15cm long rectangular metal strip .The left end bottom side of this strip consists of a fixed jaw 1 and at the same end jaw 2 at the top of this strip. On the strip a scale (5)is graduated in Inches along the upper edge and another scale(4) is graduated in Centimeters along the lower edge. This is called Main Scale 'S' .ii) A metal frame V called vernier slides over the Main Scale 'S' . At the bottom of this frame V a button 8(P) is attached,which helps to fix this vernier at any desired place on the main scale.This verier frame consists of jaw1 (B) at the bottom and a jaw 2(D) at the top .Two scales are graduated on this frame corresponding to two scales on the Main Scale 'S'. The two scales 6 and 7 on the vernier are called Vernier scale.Vernier scale consists of equal number of divisions. When we move vernier frame over the main scale, a thin strip (3) will be projected out.The projection will be exactly equal to the distance between Jaws 1(AB) i.e the thickness of the object between jaws.

The lower jaws 1,1(AB) are used to measure the thickness or external diameter of the tubes,cylinders or spheres.

The upper jaws 2,2 (CD) are used to measure the inner diameters of hallow bodies like tubes or holes.

The thin strip ( 3) is used to measure the depth of the objects like test tubes.

Theory : Principle of vernier calipers - N divisions on the vernier scale is equal to (N-1) divisions on the main scale.

N V.S.D = (N-1) M.S.D

1 V.S.D = {(N-1)/N} M.S.D

Least count (L.C) of vernier calipers : Minimum length or thickness measurable with the vernier calipers is called its least count.

Least count (L.C) = 1 M.S.D - 1 V.S.D

L.C = 1 M.S.D - {(N-1)/N} M.S.D

L.C = 1 M.S.D [ 1-{(N-1)/N}]

L.C = (1 M.S.D )/N = S/N

Where S is the value of one Main scale division and N is the number of equal divisions on the vernier scale.

Procedure : First we have to determine the least count count of the given vernier calipers.

To determine the volume of the cylinder we have to determine a)the length of the cylinder and b) radius of the cylinder and substituting these values in the equation for the volume of the cylinder we can calculate it.

Tables and calculations are elaborately explained in my blogs i) http://gyanraj.blogspot.com/2009/01/vernier-calipers.html ii)http://gyaunnrraje.wordpress.com/category/experiments/

Reference: http://gyaunnrraje.wordpress.com/category/experiments/,http://gyanraj.blogspot.com/2009/01/vernier-calipers.html