The least count of the vernier caliper is also called the vernier constant. Least count is the smallest value that can be measured by a vernier caliper. The least count of the vernier caliper is the difference between one main scale division (1 MSD) and one vernier scale division (1 VSD).

The main scale reading is the first reading on the main scale immediately to the left of the zero of the vernier scale (3 mm), while the vernier scale reading is the mark on the vernier scale which exactly coincides with a mark on the main scale (0.7 mm). The reading is therefore 3.7 mm.

Vernier constant is defined as the difference between the value of one main scale division and one vernier scale division. It is also known as the least count of vernier calliper i.e the minimum length that can be measured accurately using this instrument.

Hint: The vernier constant (V.C.) of a vernier calipers is the ratio of the smallest division on the main scale to the number of divisions on the vernier scale. The vernier constant is the least count of the instrument. Using this ratio, we will find out the value of the smallest division on the main scale.

Vernier Constant, V.C. = 1 M.S.D.-1 V.S.D. = (1-0.9) mm = 0.1 mm = 0.01cm.

In the science of measurement, the least count of a measuring instrument is the smallest and accurate value in the measured quantity that can be resolved on the instrument’s scale. Any measurement made by the instrument can be considered repeatable to no less than the resolution of the least count.

The vernier caliper uses the principle of alignment of line segments to determine the more accurate reading. The length of the object to be measured is placed in between the two jaws of the vernier calipers. Certain graduation on the vernier scale gets signed with a reading on the main scale.

You just have to add the first part and second part of the measurement to obtain the micrometer reading: 5.5+0.28=5.78 5.5 + 0.28 = 5.78 mm.

25mm

Procedure

1. Insert the sheet between the studs of the screw gauge and determine the thickness at five different positions.
2. Find the average thickness and determine the correct thickness by applying the zero error.