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Vernier Calipers
Vernier calipers are measuring instruments that are used to calculate precise linear measures. It calculates the straight linear distance between two points in layman’s terms. It could be as simple as a compass with inside and outside points. The tips of the calliper are first fixed to fit across the spots to be recorded, then the calliper is removed and the distance between the tips is evaluated with a ruler.
By positioning the caliper’s jaws on each side of the circumference, a vernier calliper can also be used to determine the diameter of circular and cylindrical objects. A Vernier calliper is an essential tool to have in your toolbox.
Vernier callipers have a primary scale on one end and a jaw on the other. The vernier scale is placed in another jaw which slides over the main scale. Whenever the two jaws come together, the main scale and Vernier scale’s zeros should match up. If two zeros do not match, there’ll be a positive or negative zero error.
Different Parts of Vernier Caliper
The Primary Scale
It is made of a steel metallic strip with one edge graded in centimetres and the other in inches. Both the inner and outer measuring jaws are included. The focal scale zeros, as well as the vernier, should line up when the two jaws inherit contact. If two zeros do not match, there will be a positive or negative zero error.
Vernier Scale
A vernier scale moves along the strip. It may be fixed in any position according to the retainer.
Outer Measuring Jaws
The outside measuring jaws assist in obtaining the outer dimension of an object.
Inner Measuring Jaws
The inside dimension of an object can be measured with the use of the inner measuring jaws.
Depth Measuring Prong
The depth measurement prong is used to measure an item’s depth.
Uses of Vernier Caliper
Vernier Calipers are most commonly used to compute the distance opposing edges of a surface. The internal and exterior dimensions of an object, as well as its height, may all be precisely measured. It boasts a one-tenth of a millimetre resolution.
To Measure Diameter of a Small Spherical cylindrical Body Using Vernier Callipers
Aim
Using Vernier Callipers, measure the diameter of a small spherical cylindrical body.
Apparatus
A magnifying lens, vernier callipers, and a spherical body (pendulum bob) or a cylinder.
Theory
If the zero of the vernier scale is ahead of the Nth. division of the main scale with the body between the jaws, then the main scale reading (M.S.R.) = N.
If the nth division of the vernier scale matches any division of the main scale, the vernier scale measurement is correct (V.S.R.)
=n×(L.C)(The least count of vernier callipers is referred to as L.C.)
=n×(V.C)(V.C. is referred to as vernier constant of vernier callipers)
T.R.=M.S.R +V.S.RL.C.=V.C.
=N+n×(V.C)
Diagram
Procedure
Calculate and record the vernier constant (V.C.) of the vernier callipers, i.e. the least count (L.C.).
Find the zero error by bringing the moveable jaw BD into close contact with the fixed jaw AC. Do it 3 times and keep track of your results. If there isn’t a zero error, set it to nil.
Open the jaws, position the sphere or cylinder between jaws A and B, and set the jaw DB so that it comfortably grips the body without exerting excessive pressure. Tighten the screw S which holds the vernier scale V in position.
Take note of where the vernier scale’s zero mark is on the main scale. Just before the vernier scale’s zero mark, note the main scale reading. This is referred to as the main scale reading (1ST) (M.S.R.).
Take note of the vernier scale division number (n), that corresponds to a division of the main scale.
After turning the body 90 degrees, repeat steps 4 and 5 to measure the diameter in a perpendicular direction.
Steps 3, 4, 5 and 6 must be repeated for three distinct positions. Make a table summary of the observations in each set.
Apply a zero correction to the overall reading.
Calculate the average of various diameter values and display the result in the appropriate unit.
Observations
Vernier Constant (Least Count) of Vernier Callipers Determination
1 M.S.D.=1 mm
10 V.S.D.=9 M.S.D
1 V.S.D=910M.S.D=0.9mm
Calculation
D=D1a+Db+D2a+D2b+D3a+D3b6
Precautions
The movement of the vernier scale on the main scale should be smooth (by oiling if necessary).
The vernier constant and zero error should be found and recorded carefully.
The body must be firmly but gently held between the teeth (without undue pressure on it from the jaws).
Measurements must be taken at right angles in one location and in at least three separate locations.
Sources of Error
On the main scale, the vernier scale may be loose.
It’s possible that the jaws aren’t at right angles to the main scale.
The scale graduations may not be accurate or clear.
In taking observations, there may be some parallax.
Conclusion
Vernier callipers are measuring instruments for determining exact linear measurements. In layman’s terms, it measures the straight linear distance between two places. A simple compass with inside and outside points could suffice.
