Aim:- To measure diameter of a small
spherical/cylindrical body using Vernier callipers.
Apparatus:- Vernier callipers, a spherical
body (pendulum bob) or a cylinder and a magnifying lens.
Theory:-
If with the body between the jaws, the zero
of Vernier scale lies ahead of Nth division of main scale, then main
scale reading (M.S.R) = N.
If nth division of Vernier scale coincides
with any division of main scale, then Vernier scale reading (V.S.R)
= n x
(L.C.) (L.C. is least count of Vernier callipers)
= n x (V.C.) (V.C. is Vernier constant of Vernier callipers)
Total reading, T.R = M.S.R + V.S.R (L.C. =
V.C.)
=N+ n x (V.C)
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Vernier callipers - Measuring diameter of a sphere. |
Observations:-
Determination of Vernier Constant (Least
Count) of the Vernier Callipers- 1 M.S.D = 1mm
1O V.S.D = 9 M.S.D
Therefore, 1 V.S.D = M.S.D = 0.9 mm.
Vernier Constant,
V.C = 1 M.S.D - 1 V.S.D =
(1 — 0.9) mm = 0.1 mm = 0.01 cm.
Zero error (i) ...... cm, (ii)..... cm, (iii)
...... cm.
Mean zero error (e) = ...... cm.
Mean zero correction (c) = - e = ...... cm.
Table for the Diameter (D):-
Mean zero error (e) = ...... cm.
Mean zero correction (c) = - e = ...... cm.
Serial Number
|
Main Scale Reading
|
Vernier Scale
Reading
|
Total Reading
|
||
No. of Vernier
division coinciding
|
Value [n x (V.C)]
|
Observed
n x V.C
|
Corrected
D = Do
+ C
|
||
1
|
|
|
|
|
D1
|
2
|
|
|
|
|
D2
|
3
|
|
|
|
|
D3
|
4
|
|
|
|
|
D4
|
5
|
|
|
|
|
D5
|
6
|
|
|
|
|
D6
|
Calculation:-
Mean corrected diameter (D) = D1
+ D2 + D3 + D4 + D5 + D6
/ 6
Result:-
The diameter of the given
sphere/cylinder is ...... cm.
Precautions:-
- Motion of Vernier scale on main scale should be made smooth (by oiling if necessary).
- Vernier constant and zero error should be carefully found and properly recorded.
- The body should be gripped between the jaws firmly but gently (without undue pressure on it from the jaws).
- Observations should be taken at right angles at one place and taken at least as three different places.
Sources of Error:-
- The Vernier scale may be loose on main scale.
- The jaws may not be at right angles to the main scale.
- The graduations on scale may not be correct and clear.
- Parallax may be there in taking observations.
Thank you
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