Vernier Calipers: Uses, Least Count, Zero Error and Reading Calculation

Physics Practical Guide

Vernier Calipers

Vernier Calipers are precision measuring instruments used to measure length, external diameter, internal diameter and depth of objects accurately.

What are Vernier Calipers?

Vernier Calipers are measuring instruments used for taking accurate measurements of small lengths. They are more precise than an ordinary metre scale because they use two scales: the main scale and the vernier scale.

Animated representation of a vernier scale sliding over the main scale.

Image: Vernier Calipers

Watch Video: Vernier Calipers

Watch this video to understand Vernier Calipers visually.

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Parts of Vernier Calipers

📏

Main Scale

The fixed scale marked in centimetres and millimetres.

🔍

Vernier Scale

The sliding scale used to get more accurate readings.

🦷

Outer Jaws

Used to measure external diameter or thickness of an object.

⭕

Inner Jaws

Used to measure internal diameter of a hollow object.

⬇️

Depth Rod

Used to measure depth of a hole or container.

🔒

Lock Screw

Used to hold the sliding scale at a fixed position while reading.

Interactive Concept Reveal

Click each button to understand important concepts.

Least Count is the smallest measurement that can be accurately measured by Vernier Calipers. Common least count is 0.01 cm or 0.1 mm.

Zero Error occurs when the zero of the main scale and the zero of the vernier scale do not coincide when the jaws are closed.

Vernier Coincidence is the vernier scale division that exactly matches with any main scale division.

Important Formula

Least Count = Value of 1 Main Scale Division ÷ Number of Vernier Scale Divisions

Vernier Reading = Vernier Scale Coincidence × Least Count

Total Reading = Main Scale Reading + Vernier Reading

Correct Reading = Observed Reading − Zero Error

How to Take Reading from Vernier Calipers

Step 1: Place the object properly between the jaws.

Step 2: Note the main scale reading just before the zero of the vernier scale.

Step 3: Find which vernier scale division exactly coincides with a main scale division.

Step 4: Multiply the vernier coincidence by the least count.

Step 5: Add main scale reading and vernier reading. Then apply zero error correction if needed.

Interactive Vernier Reading Calculator

Enter the values below to calculate the Vernier Calipers reading.

Result will appear here.

Uses of Vernier Calipers

Measurement	Part Used	Example
External Diameter	Outer Jaws	Diameter of a rod, pencil or sphere
Internal Diameter	Inner Jaws	Diameter of a hollow pipe or ring
Depth	Depth Rod	Depth of a beaker or small container
Thickness	Outer Jaws	Thickness of a coin, sheet or block

Types of Zero Error

➕

Positive Zero Error

When the zero of the vernier scale lies to the right of the zero of the main scale, the zero error is positive.

➖

Negative Zero Error

When the zero of the vernier scale lies to the left of the zero of the main scale, the zero error is negative.

Correct Reading = Observed Reading − Zero Error

If zero error is positive, subtract it. If zero error is negative, subtracting it means it gets added to the observed reading.

Common Mistakes While Using Vernier Calipers

👁️

Parallax Error

Reading the scale from a wrong angle can give an incorrect value.

🔩

Loose Grip

The object should be held gently but firmly between the jaws.

0️⃣

Ignoring Zero Error

Zero error must be checked before taking the final reading.

📐

Wrong Alignment

The object should be placed properly between the correct jaws.

Solved Example

Suppose:

• Main Scale Reading = 2.4 cm
• Vernier Scale Coincidence = 6
• Least Count = 0.01 cm
• Zero Error = 0 cm

Vernier Reading = 6 × 0.01 = 0.06 cm

Total Reading = 2.4 + 0.06 = 2.46 cm

Therefore, the measured length is 2.46 cm.

Quick Quiz

Click the correct answer.

1. Vernier Calipers are used to measure:

Small lengths accurately

Temperature

Electric current

2. The sliding scale in Vernier Calipers is called:

Metre scale

Vernier scale

Spring scale

3. Outer jaws are used to measure:

External diameter

Temperature

Mass

4. Correct reading is calculated by:

Observed Reading + Zero Error always

Observed Reading − Zero Error

Main Scale Reading only

Frequently Asked Questions

What is a Vernier Caliper?

A Vernier Caliper is a precision instrument used to measure length, external diameter, internal diameter and depth accurately.

What is the least count of Vernier Calipers?

The least count is the smallest measurement that can be accurately measured by the instrument. A common least count is 0.01 cm or 0.1 mm.

What is zero error?

Zero error occurs when the zero mark of the main scale and the zero mark of the vernier scale do not coincide when the jaws are closed.

Which part measures depth?

The depth rod of Vernier Calipers is used to measure the depth of holes, containers or small hollow objects.

Conclusion

Vernier Calipers are important measuring instruments in physics practicals. They help measure small dimensions more accurately than an ordinary scale. To get the correct measurement, students must understand the main scale reading, vernier scale coincidence, least count and zero error.

Student Tip: Always check zero error before taking any measurement with Vernier Calipers.