Verniers Calipers | Physics Practical XI
NAME OF EXPERIMENT : TO USE A VERNIER CALIPERS TO DETERMINE THE VOLUME OF THE GIVEN TUBE.
APPARATUS REQUIRED : (i) Vernier calipers (ii) Given Tube
THEORY : The vernier calipers is a device used for measuring lengths in fractions of a millimeter with greater accuracy as compared to that of ordinary scale . It consists of main scale (MS) and vernier scale (VS) . The vernier scale (VS) slide over the main scale while main scale (MS) is fixed.
The vernier constant (VC) of the smallest length that can be measured accurately . It is the difference between the values of the smallest division of the main scale (MS) and that of the vernier scale (VS). i.e.
VC = MS – VS (I)
n division of the vernier scale (VS) coincide with
n-1 divisions of the main scale (MS) , So –
(n-1) MS = n VS
or, MS – VS = MS / n
∴ VC = value of smallest main scale Division (MSD) ÷ Total Vernier Scale Division (VSD)
∴ Length = MS reading + VS reading * VC ± Instrumental Error
FOR VOLUME :
l = length of the tube
d1 =external diameter of the tube
d2 =internal diameter of the tube
We have ,
external volume(V1) = π/4 (d1)2l
internal volume(V2) = π/4 (d2)2l
∴ Volume of the tube (V) = V1-V2
∴ V = πl/4*(d22-d12)
a) Determination of Vernier Constant (Least Count) of the Vernier Calipers :
1 division of main scale = 1mm (MS)
10 VSD = 9 MSD
∴ 1 VSD = 9/10 MSD = 0.9 MSD = 0.9mm(VS)
∴ Vernier Constant (VC) = MS – VS = 1mm – 0.9mm = 0.1mm = 0.01cm
b) Measurement of volume :
Measurement with vernier calliper
|Obs for||No. of Obs||Reading of the||Total
(1) + (3)
|MS (1)||VS (2)||VS*VC (3)|
|Ext. Diameter (d2)||1||d2 = …..cm|
|Int. Diameter(d1)||1||d1 =….cm|
∴ Volume of the tube (V) = πl/4*(d22-d12) = ……… cm3
RESULT : The volume of the given tube is …… cm3.
a) Ensure that the zero error is worked out properly before actual measurement.
b) Donot aapply excess pressure on the bodyheld between jaws.
c) All measurement must be done without parallax error.
d) Record all the reading in same system preferably in C.G.S system .