Vernier caliper

Vernier caliper : vernier caliper definition , vernier caliper least count , vernier caliper diagram , vernier caliper least count formula

Introduction:

Measurement is a fundamental aspect of any experimental science and Physics is no exception. Of the various measurable quantities, length and width is a quantity that we frequently require to measure. which our measure by vernier caliper. The main use of the vernier caliper is to used for measure the internal and external diameters of an object. A vernier caliper is an instrument which is most commonly used for a variety of exact measurements.

What is measurement?

Measurement An action that is performed by someone.  some Kinde of a target’s size, length, weight, and capacity. There are a number of terms similar to “measure” but which vary according to the purpose (such as “weight,” “calculate,” and “quantify.”) In general, measurement can be understood by “instrumentation.”

What is vernier caliper?

A vernier caliper is an instrument. that is used for the measurement of linear dimensions.  It can measure 100th part of 1 millimeter. It can measure length, diameter, thickness, depth etc.     

It is also used for the measurement of diameters of round objects with the help of the measuring jaws. which is most commonly used for a variety of exact measurements, it have necessarily to the engineering manufacturer.

vernier caliper diagram

The Invention of vernier caliper

The vernier caliper was invented by French mathematician Pierre Vernier. That had ability to make very fine measurements. It was designed to measure linear distances very accurately. and the modern Vernier caliper was invented by Joseph R. Brown in 1851. It was the first practical tool for low and high distance exact measurement. that could be sold at an affordable price to ordinary machinists.

Vernier caliper least count

The least count of a common scale is 1mm. It is difficult to further subdivide it to improve the least count of the scale. A vernier scale enables this to be achieved.

The difference in the magnitude of one main scale division (M.S.D.) and one vernier scale division (V.S.D.) is called the least count of the instrument, as it is the smallest distance that can be measured using the instrument.

n V.S.D. = (n – 1) M.S.D

Formulas Used:

(a) Least count of vernier caliper = the magnitude of the smallest division on the main scale / the total number of small divisions on the vernier scale.

(b) Density of a rectangular body = mass/volume = m/v = m/l.b.h where m is its mass, l its length, b its breadth and h the height.

(c) The volume of a cylindrical (hollow) object V = πr²h´= πD´²/4. h´ where h’ is its internal depth, D´ is its internal diameter and r is its internal radius.

Types of vernier calipers

There are mainly seven types of vernier calipers:

1. Flat edge vernier caliper
2. Knife edge vernier caliper
3. Vernier gear tooth caliper
4. Vernier depth gauge
5. Flat and knife edge vernier caliper
6. Vernier height gauge
7. Vernier dail caliper

Vernier caliper parts

Outside jaws: Used to measure external dimensions.
Inside jaws: Used to measure internal dimensions.
Depth probe: Used to measure depth of containers.
Main scale (in cm)
Main scale (in inch)
vernier scale (in cm)
vernier scale (in inch)
Retainer: Used to block movable parts.

Main elements of the vernier caliper

The main elements of the vernier caliper are the:

• Main Scale marked in inches and fractions.
• Vernier scale gives interpolated measurements to 0.1 mm or better.
• Vernier scale gives interpolated measurements in fraction of an inch.
• Thumbscrew is located at the bottom of the vernier scale.
• Lock screw is used to fix the position of the jaws once the object is positioned.
• Depth Bar can be used to measure the depths of holes or steps.
• Outside jaws used to measure external diameter or width of an object.
• Inside jaws used to measure internal diameter of an object.
• Thumb grip used to block movable part to allow the easy transferring of a measurement.

How to used vernier caliper ?

A Vernier caliper has two scales–one main scale and a Vernier scale, which slides along the main scale. The main scale and Vernier scale are divided into small divisions though of different.

Main Scale

It is a large scale that runs along the body of the vernier caliper. The reading on the main scale could be either in centimetres or millimetres depending on the usage. 1 mm is the lowest main scale division according to the SI units.

vernier scale

On a ruler with a coarse scale, least count of 1 cm, the specimen is between 3 and 4 cm, and we estimate it to be about 3.3 cm.

On a ruler with a finer scale, least count of 0.1 cm, the specimen is between 3.3 and 3.4 cm, and we estimate it to be about 3.38 cm.

The ability to use high precision scales is limited by the spacing between the marks. Thus it is easy to have a least count of 1 mm, more difficult to have a least count of 0.2 mm, and virtually impossible to have a least count of 0.002 mm, a human hair has a diameter of about 0.050 mm. In order to increase precision we need an auxiliary scale called a vernier scale. 

lower Jaws

These jaws are considered to be one of the most prominent features of vernier caliper. One of the jaws is fixed and attached to the main scale. While the other jaw is movable and is attached to the vernier scale. These jaws are designed mainly to grip the objects firmly. The main function of the lower jaw is to measure the outer dimensions such as diameter, width and length.

Upper jaws

Upper jaws used to measure external diameter or width of an object.

lock screw

The main use of a lock screw is to fix the position of the jaws after the object is firmly fixed between the jaws. This also makes it easier to take proper readings. which gives us an accurate measurement.

Thumb Screw

Thumb grip used to block movable part to allow the easy transferring of a measurement. This screw is located at the bottom of the vernier scale. The main function of the thumbscrew is to provide grip to the users so that the sliding of the jaws becomes easy.

Vernier Caliper Least Count

The difference between the value of one main scale division and the value of one Vernier scale division is known as the least count of the Vernier. The least count of vernier caliper is also known as the vernier constant. It is defined as the difference between one main scale division and one vernier scale division.

Depth Rod

Depth Rod used to measure the depths of holes or steps. The depths of the jars can be measured using the depth rod. It is a thin rod located at the end of the main scale. The edge of the main scale is placed on the top surface of the object, then the jaws are slowly opened. The opening of the jaws results in the extension of the depth rod. Until the depth rod reaches the bottom of the object, the jaws need to be opened.

What is Zero Error?

Zero error in the vernier caliper is a mathematical error due to which, the zero of the vernier scale does not coincide with the zero of the main scale. In other words, if the zero mark on the vernier scale doesn’t coincide with the zero mark on the main scale, then the error that occurs is called zero error. They are of 2 types:

• Positive Zero Error
• Negative Zero Error

1. Positive zero error

A positive zero error is when the zero mark on the vernier scale lies ahead of the zero mark on the main scale in the closed position, i.e the reading is greater than zero or positive. For example In positive zero error, let’s bring these jaws together.

You see, the zero of vernier scale is ahead of main scale zero. Or you can say zero of vernier scale is at the right side of main scale zero. In both cases either it is ahead of main scale zero or it is the right side of main scale zero. this is called as zero error and it is positive.

2. Negative zero error

If two jaws of vernier touches together & if the 0 of vernier scale remains on left hand side with 0 of main scale than error is said to be zero error.

Frequently Asked Questions – FAQs