# Measurement Of Length / Distance (Metre Rule, Vernier Caliper Reading Examples, Exercise And Others)

## Length:

Length is the amount of the space between two locations. Length can be measured using instruments like tape rules, metres rule micrometer screw gauges, etc.

Lesser length distances are measured with the vernier caliper or Micrometer Screw Gauge.

### Metre Rule:

Meter rule is a tool which is used to determine the length of various objects. They are calibrated to millimeters as well as centimeters.

A meter rule with a length of 1m is equivalent to 100 centimeters (cm). According to the meter rule, each centimeter is further divided into 10 parts, and these are known as millimeters (mm).

Certain meter rules are calibrated in feet or inches. The accuracy of reading the metre rule is 1 millimetre or 0.1 centimeters.

### Vernier Calliper:

Vernier caliper can be used to measure small dimensions (0-15cm). The calipers are useful for measuring the diameter of objects that are circular. It is able to read with a precision of 0.01cm. Vernier scales consist of an primary scale (m) and an auxiliary scale (s). The jaws outside serve to determine the dimensions of the outside of the object, while the jaws within are used to measure inside or internal dimensions. To determine the measurement, lightly grip the object with straight edges of the outside and inside jaws.

Accuracy of Vernier Calliper:

The precision of a vernier caliper is 0.1 millimeters or 0.01 centimeters. That means that the lowest distance that the vernier caliper is able to determine is 0.1 millimeters, or 0.01 centimeters.

### How to Read Vernier Calliper: Place the object in between and the jaws on the caliper, and stop the jaws so that the item is secured with a firm grip.

Find the reading on the main scale prior to the zero (0) on the scale called the vernier. Find the marks on the scale of the vernier that match the markings of the principal scale.

Multiply the reading on the scale of the vernier by the precision of the scale that is 0.01 centimeters

Example 1  In the above figure Find the position in the main scale in the figure above, which is just prior to the zero mark of the vernier scale. In the image the scale is located between 6.10cm and 6.10cm.

Locate the marking on the scale of the vernier closest to each mark in the scale. These six marks are the closest match when compared to the mark that is on the main scale.

Multiply the reading from the scale of the vernier by the precision of the scale, which is 0.01 centimeters.

= 6 x 0.01 cm = 0.06 cm

Combine the two values to calculate the final reading:

6.10 cm + 0.06 cm = 6.16 cm

Example 2 Principal Scale reads: 10.0 cm (Immediate left of zero)

Scale Vernier reading 2. (Alignment between scale lines)

Reading of vernier scales with x precision of vernier scale

2 x 0.01 cm = 0.02 cm

= 10.02cm

Example 3

In this instance the vernier scale measures in millimeters. Be aware that the accuracy of the vernier caliper is 0.1 millimeters or 0.01cm. We’ll be using 0.1 millimeters in this case. In the above figure In the figure above, locate the point in the main scale in the figure above, which is just in front of the zero mark of the vernier scale. In the illustration the scale is located between 3.70 centimeters or 37 millimeters.

Look for the marks on the scale of the vernier that is closest to each mark in the scale. Here, 4.6 aligns best with any mark on the primary scale. The scale is in millimeters.

Multiply the reading from the scale of the vernier by the precision of the scale that is 0.1 millimeters.

= 4.6 x 0.1 mm = 0.46 mm

Combine the two values to calculate the final reading:

37 mm + 0.46 mm = 37.46 mm

### Micrometer Screw Gauge: It is designed for quick readings that range from 0 to 2.5 cm. The accuracy of readings with this micrometer can be as low as 0.001 millimeters or 0.1 millimeter. Micrometers come with two scales: the primary scale (on the sleeves) as well as the vernier/circular scale (on the thimble).

The primary scale equals 1 millimeter while the scale on scale of the vernier is 0.01 millimeters. ### How to Read Micrometer Screw Gauge:

• Rotate the thimble to ensure that the object securely held.
• Take the reading of the main scale on the sleeve. It’s in millimeters.
• Look up this line from the scale which is parallel to the main scale’s line.
• Multiply the reading on the scale of the vernier by the precision of the scale, which is 0.01mm.
• In the end, you can add the readings on the principal scale with the reading from the vernier scale to get results in millimeters.

Example 1 Main scale (sleeve) reading: 3.50 mm

The reading on the scale of vernier is: 27

Reading of vernier scales with x precision of vernier scale

= 27 x 0.01 mm

= 0.27 mm

Mandatory reading: 3.50 millimeters + 0.27 mm = 3.77 mm

Example 2 Main scale (sleeve) reading: 7.00 mm

The reading on the scale of vernier is: 38

Vernier scale reading the accuracy of vernier scale

= 38 x 0.01 mm

= 0.38 mm

Mandatory reading: 7.00 mm + 0.38 mm = 7.38 mm

## Worked Examples – Reading A Vernier Calliper / Micrometer Screw Guage

Worked Example 1:

What does the reading on the vernier caliper, as illustrated in the below figure? The reading of the principal scale (before the 0 on the vernier scale) is 10.0 cm

Reading from the vernier scale = 2.

Reading of vernier scales x precision of the vernier calliper

= 2 x 0.01 cm = 0.02 cm

The final reading is Main scale plus Vernier scale

10.0 cm + 0.02 cm = 10.02 cm

Worked Example 2:

What does the reading on the vernier caliper, as illustrated in the image below? Readout of principal scale (before zero on the Scale Vernier) equals 4.3 cm

The reading of the Vernier Scale = 5

Reading of vernier scales x precision of the vernier calliper

= 5 x 0.01 cm = 0.05 cm

Last reading: Main scale + Vernier scale = 4.30 cm plus 0.05 centimeters

So, reading of vernier’s calliper is 4.35 centimeters.

Worked Example 3:

What do you think is the value of the micrometer meter screw gauge depicted in the picture below? Readout of principal scale is 3.00 millimeters

Reading on the vernier scale = 9

Reading of vernier scale accuracy of scale of vernier = 9 x 0.01 millimeters = 0.09 millimeters

Add the results from the primary scale (vernier scale x precision that of the Vernier scale) to calculate the reading of the micrometer gauge.

= 3.00 + 0.09 = 3.09 mm

Reading of the micrometer screw gauge is 3.09 millimeters

Worked Example 4:

What does the reading on the micrometer meter screw gauge illustrated in the image below? Readout of principal size = 22.0 millimeters

Reading from Vernier Scale = 33

Vernier scale reading and precision of vernier scale

= 33 x 0.01 = 0.33 mm

Add the results for the principal scale (vernier scale x precision that of the the vernier scale) to determine the measurement of the micrometer screw gauge.

= 22.0 + 0.33 = 22.33 mm

Reading of the screw guage = 22.33 millimeters

Worked Example 5:

What do you think is the value of the micrometer meter screw gauge depicted in the picture below? Readout of principal scale is 7.50 millimeters

Vernier scale = 22. the vernier scale = 22

Reading of the vernier scale x precision of the scale 22 x 0.01 millimeters = 0.22 millimeters

Add the results for the principal scale (vernier scale x the accuracy from the vernier scale) to determine the reading of the micrometer gauge.

= 7.50 + 0.22 = 7.72 mm

The reading of the micrometer meter screw gauge is 7.72 millimeters