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Vernier Calliper was invented in the year 1631 by Pierre Vernier of France. It was invented as a tool to determine highly accurate linear measurements. A vernier caliper has two graduated scales: a primary scale and a specifically graduated auxiliary scale. This scale slides parallel to the main scale and provides readings in the fraction of a division on the main scale.
Vernier Caliper helps to take accurate measurement reading between two graduation markings on a linear scale. Vernier calipers use mechanical interpolation that increases resolution and reduces measurement uncertainty by using vernier acuity to reduce human estimation error. Vernier calipers are used in scientific laboratories and in manufacturing for quality control measurements. A vernier scale has 25 divisions, whereas the main scale has 24 divisions in the same length.
Also Read: Dimensional Analysis
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Key Terms: Vernier Scale, Verniers, Uses of Vernier Caliper, Digital Vernier Caliper, Slide Calipers, Depth Measuring Prong
What are Vernier Calipers?
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Vernier calipers are tools used to calculate exact linear measurements. It calculates the straight linear distance between two locations. It might be as basic as a compass with points pointing inside or outward. The caliper’s tips are first adjusted to fit across the points to be measured, then the caliper is withdrawn and the distance between the tips is measured with a ruler.
Vernier Calliper Diagram
A vernier caliper may also be used to measure the diameter of circular and cylindrical objects by placing the caliper's jaws on each side of the circumference. A Vernier caliper is an extremely important item to have in your toolkit.
Diagram of Vernier Caliper
Vernier calipers are made up of a primary scale with a jaw at one end. Another jaw slides over the main scale, housing the vernier scale. When the two jaws come into contact, the zeros of the main scale and the Vernier scale should line up. There will be a positive or negative zero mistake if two zeros do not coincide.
How to Use Vernier Calipers?Typically, a vernier caliper is used to measure the diameter of circular objects. The vernier caliper's round jaws precisely suit the circumference of round objects. A vernier caliper has two scales: a fixed main scale and a movable vernier scale. The primary scale displays measurements in millimeters. Unlike ordinary scales, a vernier caliper can precisely measure values up to 0.001 cm. A vernier scale, in conjunction with a vernier caliper, is used for precise measurement. |
Different Parts of Vernier Caliper
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- The Primary Scale: It is made out of a steel metallic strip that is graded in centimeters on one edge and inches on the other. It is equipped with both the inner and outer measuring jaws. When the 2 jaws inherit contact, the zeros of the focal scale and also the vernier should line up. There will be a positive or negative zero mistake if two zeros do not coincide.
- Vernier Scale: On the strip, a vernier scale slides. The retainer allows it to be fastened in any position. 0.9 cm is split into 10 equal pieces on the Vernier scale.
- Outer Measuring Jaws: The outside measuring jaws aid in taking an object's exterior dimension.
- Inner Measuring Jaws: The inner measuring jaws aid in taking an object's interior dimension.
- The Retainer: The retainer aids in keeping the item in the Vernier calipers' jaws.
- Depth Measuring Prong: The depth measuring prong aids in determining the depth of an item.
Difference Between Main Scale and Vernier ScaleVernier scale has 25 divisions while the main scale has 24 divisions in the same length. Thus, divisions on vernier scale are shorter than those on the main scale by 1/25 of a division on the main scale.
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Uses of Vernier Caliper
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The primary application of Vernier Calipers is to measure the distance between two opposing sides of a surface. We can precisely measure an object's interior and exterior dimensions, as well as its height. It has a resolution of one-tenth of a millimeter.
Uses of vernier calipers and its applications are listed below and explained further in the article:
- Sector of Education
- Science Laboratories
- Medical Purposes
- Steel Industries
- Aerospace industries
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Vernier Caliper Uses in Education Sector
- One of the most common applications for this device is in this sector. It is used to investigate the expansion of materials as a result of temperature changes in order to determine their characteristics.
- It is used to measure various pieces of equipment in order for them to fit properly. They are also useful for measuring regular and irregular-shaped items from the inside or outside.
Usage of Vernier Calipers in Science Labs
- Vernier calipers are used for a wide variety of tasks in scientific laboratories. For example, to investigate the influence of temperature changes in various metals with varying chemical characteristics.
- Vernier calipers are also used to accurately measure things that are required to connect two sections of two objects, requiring high accuracy.
Vernier Calipers are Used for Medical Applications
- Since the dimensions of medical equipment must be measured with the greatest precision for medical usage, surgical tools in the medical industry use vernier calipers.
- Because the size of tools has been measured in order to be optimal for surgery, the medical and surgical industries rely heavily on this equipment.
- Accuracy and precision are important here since every instrument is very sensitive to even minor changes and must be measured accurately in order to work in a highly complex environment.
Vernier Calipers Used in Steel Sector
- The use of a vernier caliper is strongly advised when producing or inspecting the dimensions of a by-product to guarantee the necessary requirements are fulfilled. It is used to determine the length, breadth, and even height of various things.
- It is useful for measuring holes, the width of pipes, the circumference of metal beads, and so forth. The Vernier caliper is an essential tool in the steel industry. It is used to determine the interior and exterior dimensions of steel-made items. It is also used to determine the thickness of steel items of various forms.
Uses of Vernier Calipers in Aerospace Sector
- The aviation business relies on absolute accuracy; even a minor alteration in the size of an object can be disastrous. The usage of this gadget here ensures that safety criteria are met, as well as precision in the use of small parts, which aids in flying.
- Without a doubt, the aerospace aviation sector needs great accuracy. Even a minor change in the dimensions of an object can cause significant damage to it and its surroundings. To address such system damage, several types of vernier calipers with high precision readings, such as digital dial calipers, are utilized.
What is Zero Error?
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Zero error is the condition in which the measuring device registers a reading when it should not register a reading. The zero error of the vernier caliper is calculated as:
| Actual reading = Main scale + Vernier scale – (Zero error) |
There are two categories of zero error:
- Positive zero error: When the jaws of the vernier caliper are closed and the reading is positive and away from the actual reading of 0.00 mm. For instance, if the reading is 0.08 mm, then the zero error is +0.08 mm.
- Negative zero error: When the jaws of the vernier caliper are closed and the reading is negative and away from the actual reading of 0.00 mm. For instance, if the reading is 0.10 mm, then the zero error is -0.10 mm.
Vernier Calipers: Range and Least Count
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The difference between the largest and smallest measurement readings determines a vernier caliper's maximum capacity. Typically, it is the whole length of the vernier caliper's primary scale. The standard range of vernier calipers is 300 mm. However, lower-range vernier calipers are also available on the market.
Range of Vernier Calipers
Difference between largest and smallest measurement reading determines the maximum capacity of a vernier calliper. It is the entire length of the main scale of the vernier caliper. Vernier calipers generally have a range of 300 mm. Vernier calipers of smaller ranges are also available.
- Vernier Reading: Smallest measurable distance that can be captured by a vernier caliper is called a vernier reading. It is also called as "Resolution" of a vernier caliper. Vernier calipers normally have a resolution of 0.001 inches, and resolution or smallest measurable distance of a metric vernier caliper ranges from 0.02 mm to 0.05 mm. Vernier reading is provided at the end of a Vernier scale.
- Tolerance: Tolerance (also called instrument error) is accuracy of the readings of a Vernier caliper. Vernier calipers help in calculation of low tolerance measurement readings. Low tolerance measurement readings provide accurate results because probability of error is minimum. Tolerance of the Vernier calipers is about +/- 0.03mm (+- 0.0015 in).
Least Count
The smallest count or reading obtained with the instrument can be computed as follows:
Least Count = One Main Scale Division – One Vernier Scale Division
or
| \(\text{Least Count} = \frac{\text{One main Scale Division}}{\text{No. of Divisions in Vernier Scale}}\) |
In case there are n divisions on vernier scale coinciding with (n-1) division on the main scale, the least count of vernier calliper will be:
| \(LC = (1-\frac{n-1}{n})MSD\) |
Things to Remember based on Uses of Vernier Calipers
- Applications of vernier calipers:
- We can measure the length of a rod, the diameter of a sphere, and the outer diameter of a hollow cylinder with the vernier's outer jaws.
- The inner jaw can be used to measure interior dimensions such as pipe inner diameter, seals, and washers.
- The depth or length of the bottle or beaker can be measured by using the stem.
- Measurement of workpiece thickness.
- To measure shaft diameter, keyway dimensions, shaft length.
- For measurement of Slots, undercut groves.
- The vernier caliper operates on the concept that when two scales or divisions of slightly different sizes are used, the difference between them is utilized to improve the measurement accuracy.
- Advantages:
- Amplification is done through design and it doesn’t rely on the parts that wear over time.
- Interpolation is not possible in reading, let alone required.
- Zero setting adjustment is easy.
- There is no theoretical limit to the scale range.
- Disadvantages:
- The main disadvantages occur in the instruments on which verniers are used.
- The reliability of reading usually depends upon the observer.
- No way to adjust for any errors other than zero settings.
- The Use of vernier calipers is an indispensable topic for a student from a board exam point of view. It is a part of Chapter-2 in physics which is ‘UNITS AND MEASUREMENTS’. The chapter delineates the significance of units and measurements and measurements of time, length, etc.
Previous Year Questions
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Sample Questions based on Uses of Vernier Calipers
Ques. What is the difference between a vernier and a caliper? (2 Marks)
Ans. A caliper is a device used to measure the thickness of an object's two surfaces, whereas a vernier is a sort of secondary scale having smaller graduations (for accurate measurements) than a measuring instrument's primary scale. The vernier scale takes readings between the bigger scale's graduations.
Ques. What are the different types of vernier calipers? (3 Marks)
Ans. According to Indian standards, there are three types of vernier calipers.
- The first type of caliper features jaws on both sides for internal and exterior measurements, as well as a depth gauge. These vernier calipers are typically constructed of steel with a hardness of around 65050 HV (Vickers Pyramid Number). The earliest type of vernier caliper is seen in the figure below.
- The second type of vernier caliper does not have separate jaws for exterior and interior measurements. It has a single pair of jaws for measuring both exterior and interior dimensions. The measuring faces of the jaws of the second kind of vernier caliper may take exterior and interior measurements.
- The Third type of vernier caliper is identical to the second kind. The only distinction is that it has a knife edge that may be used for marking.
Ques. What precautions should be taken when using the Vernier Caliper? (3 Marks)
Ans. The narrower jaws of a vernier caliper are used to measure an object's interior diameter. The exterior diameter is measured using the main jaws.
The Vernier Scale: A caliper has a fixed main scale and a sliding (Vernier) scale. In addition, the vernier scale includes an etched label that shows the value it represents.
Unlocking the Screw: Some vernier caliper types have a locking screw. Before using the vernier caliper, make sure the screws are unlocked. Unlocking the screw requires a counterclockwise twist.
Ques. How to use vernier caliper? (4 Marks)
Ans. Vernier Scale is used to measure the length of an object or the outer diameter of a cylindrical object.
It has a main scale and a smaller scale called the Vernier scale that slides over the main scale. This instrument has two pairs of jaws that are used to hold objects to be measured.
The object to be measured is fixed between the two jaws, lengthwise for length measurement. If measuring diameter, the cylindrical side of the object should be fixed between the two jaws. To measure the inner diameter of a cylindrical object, that object should be fixed over the smaller upper jaws, with the jaws touching the inside walls of the object.
- To obtain the correct measurement with a Vernier caliper we have to first find the least count of the instrument. You also have to determine the zero error of the instrument.
- The observed reading will be the main scale reading added to the product of the Vernier scale reading and the least count.
- The true measurement will then have to account for the zero error. So, the final measurement will be the observed reading ± the zero correction.
Ques. The least count of Vernier caliper is:
(i)Maximum measurement on main scale/Total number of divisions on the scale
(ii)Minimum measurement on main scale/ total number of divisions on Vernier scale
(iii)Maximum count on scale/ Minimum count on the scale
(iv)None of these (4 Marks)
Ans. The length measured by the smallest division in any measuring device has the lowest count. When we think of Vernier calipers, we must remember that they have two scales: the primary scale and the Vernier scale. The fixed value or fixed scale is the main scale.
The changing or sliding scale is known as the Vernier scale. The difference between MSD and VSD is defined as the least count of the Vernier scale, where MSD is the main scale division and VSD is the Vernier scale division.
Alternatively, the least number of Vernier calipers can be calculated as the ratio of the minimum measure on the main scale to the total number of divisions on the Vernier scale. Therefore the correct answer is OPTION B.
Ques. Vernier calipers have 1mm marks on the main scale. It has 20 equal divisions on the Vernier scale which matches with 16 main scale divisions. For this Vernier calipers, the least count is:
(i)0.02 mm
(ii)0.05 mm
(iii)0.1 mm
(iv)0.2 mm (5 Marks)
Answer: Practically there can’t be a measurement where the error becomes totally zero. Every measurement has a certain amount of error which could be human error, instrument error, or any other error. But it is a good practice to minimize this error as much as possible.
The use of scale in the measurement will result in a huge value of error. Whereas if we use a Vernier caliper, we reduce the error of measurement.
Now, given main scale reading (M.S.D) = 1 mm
Also 1VSD = 16/20 MSD,
where VSD means vernier scale reading and MSD means main scale reading.
Thus, using
L.C = 1MSD − 1VSD
L.C = 1MSD − 16/20 MSD = 1/2 MSD
⇒ LC = 1/5 (1mm) = 0.2mm
So, the correct answer is “Option D.
Ques. Diameter of a steel ball is measured using a vernier callipers which has divisions of 0.1cm on its main scale (MS) and 10 divisions of its vernier scale (VS) match 9 divisions on the main scale. Three such measurements for a ball are given as:
If the zero error is – 0.03 cm, then find the mean corrected diameter. (5 Marks)
Ans. MSD = 0.1 cm
VSD = 9/10 MSD = 0.9 × 0.1= 0.09 cm
Least count = MSD – VSD = 0.1 – 0.09 = 0.01 cm
Total reading = Main Scale Reading + Vernier coincidence × Least Count
1st reading = 0.5 + 8 × 0.01 = 0.58 cm
2nd reading = 0.5 + 4 × 0.01 = 0.54 cm
3rd reading = 0.5 + 6 × 0.01 = 0.56 cm
Average reading = (0.58 + 0.54 + 0.56)/3 = 0.56 cm
Corrected reading = reading – zero error = 0.56 – (-0.03) = 0.56 + 0.03 = 0.59 cm
Ques. The diameter of a cylinder is measured using Vernier callipers with no zero error. It is found that the zero of the Vernier scale lies between 5.10 cm and 5.15 cm of the main scale. The Vernier scale has 50 divisions equivalent to 2.45 cm. The 24th division of the Vernier scale exactly coincides with one of the main scale divisions. The diameter of the cylinder is:
(i) 5.112 cm
(ii) 5.124 cm
(iii) 5.136 cm
(iv) 5.148 cm (3 Marks)
Ans. Smallest main scale division = 0.05 cm (5.15 – 5.10)
Main scale reading = 5.10 cm (comes just before the zero of the Vernier scale)
Vernier coincidence = 24
Least count =0.05 – 2.45/50 = 0.001 cm
Diameter
= Main Scale Reading + Vernier coincidence × Least Count
= 5.10 + 24 × 0.001 = 5.124 cm
Ques. The main scale of a vernier callipers is calibrated in mm and 19 divisions of main scale are equal in length to 20 divisions of vernier scale. In measuring the diameter of a cylinder by this instrument, the main scale reads 35 divisions and 4th division of vernier scale coinsides with a main scale division. Find:
(i) Least count
(ii) Radius of cylinder (3 Marks)
Ans. (i) MSD = 0.1 cm
20 VSD = 19 MSD
⇒ VSD = 19/20 MSD = 19/20 × 0.1 cm = 0.095cm
Least Count = MSD – VSD = 0.1 – 0.095 cm = 0.005 cm
(ii) Main scale reading = 35 mm = 3.5 cm
Diameter
= Main scale reading + vernier coincidence × Least count
= 3.5 + 4 × 0.005
= 3.5 + 0.02
= 3.52 cm
Radius = Diameter/2 = 3.52/2 = 1.76 cm
Ques. The jaws of a vernier callipers touch the inner wall of calorimeter without any undue pressure. The position of zero of vernier scale on the main scale reads 3.48. The 6th of vernier scale division is coinciding with any main scale division. Vernier constant of callipers is 0.01 cm. Find actual internal diameter of calorimeter, when it is observed that the vernier scale has a zero error of – 0.03 cm.
(i) 3.37 cm
(ii) 3.57 cm
(iii) 3.42 cm
(iv) 3.54 cm (3 Marks)
Ans. Main scale reading = 3.48 cm
LC = 0.01 cm
Vernier coincidence = 6
Reading = Main scale reading + Vernier coincidence × LC
= 3.48 + 6 × 0.01
= 3.48 + 0.06
= 3.54 cm
Corrected reading = reading – zero error
= 3.54 – (-0.03)
= 3.54 + 0.03
= 3.57 cm
Ques. There are two Vernier calipers having 1 cm divided into 10 equal divisions on the main scale. Vernier scale of one of the calipers (C1) has 10 equal divisions that correspond to 9 main scale divisions. Vernier scale of the other caliper (C2) has 10 equal divisions that correspond to 11 main scale divisions. Readings of two calipers are shown below.
The measured values (in cm) by calipers C1 and C2, respectively, are:
(i) 2.87 and 2.86
(ii) 2.85 and 2.82
(iii) 2.87 and 2.87
(iv) 2.87 and 2.83 (3 Marks)
Ans. MSD = 1/10 cm = 0.1 cm
For the first vernier caliper,
10 VSD = 9 MSD ⇒ VSD = 9/10 MSD = 0.9 × 0.1 = 0.09 cm
Reading = main scale reading upto coinciding main scale division − n × VSD
= 3.5 – 7 × 0.09 = 3.5 – 0.63 = 2.87 cm
For the second vernier caliper,
10 VSD = 11 MSD ⇒ VSD = 11/10 MSD = 1.1 × 0.1 = 0.11 cm
Reading = 3.6 – 7 × 0.11 = 3.6 – 0.77 = 2.83 cm
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