How To Measure The Length of Cylinder Using a Vernier Caliper?

Although a common and easy method of measuring the length of a cylinder or any object is to use the metre rule but in many situations more accuracy and precision may be required. In such situations the use of a vernier caliper helps to overcome the shortcomings of the metre rule and provide a better way to measure the length. Vernier Caliper practice for finding cylinders’ dia & volume and can read here in detail.

The foremost advantage of the vernier caliper is the greater accuracy (0.01 mm) compared to the ruler (0.1 mm). Another big problem is overcoming the parallax error which may affect the reading significantly in a ruler but the vernier caliper offers a reduced error thanks to its jaws which grip the object exactly from the ends.

Cylinder Vernier Caliper
Vernier Caliper Measuring Length of Cylinder

Parallax error may also be introduced of the ends of the object are not smooth so the length may vary at different points but with a vernier caliper we can take readings from different points and take the average to eliminate the error. Metre rules also experience wear and tear on the ends which may erase some of the markings at the end of the rule which makes it difficult to measure properly. All these advantages make the vernier caliper quite an attractive tool when it comes to measuring lengths and now we will explain the procedure of using the vernier caliper to measure the length of a cylinder or any other object.

 To find the length of the cylinder/Object:

  1. Hold the cylinder from its ends using the lower jaws of the vernier caliper.
  2. Note the reading on the main scale that lies just to the left of the vernier scale zero mark. This is the Main Scale Reading (M.S.R).
  3. Now look for the mark on the vernier scale which lines up with a mark on the main scale. Count the number of divisions up to that mark. This is known as the Vernier Coincidence which is denoted by n.
  4. Multiply the Vernier coincidence with the least count to get the Vernier Scale Reading (V.S.R.)
  5. Now find the Total reading by adding the Vernier Scale reading to the Main Scale Reading.
  6. Calculation of The Length of the cylinder :

To eliminate any possible sources of error we must repeat our measurements holding the cylinder from a slightly different point between the jaws. Note down the values of Main Scale Reading, Vernier Coincidence and Vernier Scale Reading.You can use Microsoft Word or Excel to make a table with headings as shown below.

Now note down the Main Scale Readings and the Vernier Coincidence in their respective columns and use them to find the Vernier Scale Reading and the Total reading. The procedure should be repeated a number of times and the average of the total readings should be taken. This would be your final mean value for the length of the cylinder.

S.No Main Scale reading                (cm) Vernier Coincidence   (n) Vernier Scale Reading   b=(n-x)*L.C Total Reading (a+b) cm
Average length of the cylinder l = ……… cm.

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