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Practice On Reading A Vernier Caliper

Key idea: Vernier caliper reading practice (no zero error): 9 diagram questions with worked answers in cm to help O Level Physics students.

  • G3 Physics topic extensions
On this page

Learning objectives

  • Read an analogue vernier caliper scale and correct the reading for zero error

1. Definition

A. What you are practising

Practise reading a vernier caliper (no zero error). For each question, give the observed reading in cm to 0.01 cm.

If you need a refresher, use: How To Use Calipers (Digital + Vernier).

2. Key Ideas

  • Main scale reading: the value immediately left of the vernier zero.
  • Vernier reading: the aligned vernier division × 0.01 cm.
  • Observed reading = main scale + vernier reading.

3. Detailed Explanations

A. Quick workflow (exam-friendly)

  1. Write the main scale reading (to 0.1 cm).
  2. Write the vernier reading (aligned division × 0.01 cm).
  3. Add them to get the observed reading (to 0.01 cm).

4. Common Mistakes

A. Reading mistakes

  • Using the main-scale value to the right of the vernier zero.
  • Picking a line that “almost” aligns (choose the best alignment).
  • Writing the unit wrongly (mm vs cm).

5. Exam Tips

A. What markers like to see

  • Show the two parts clearly: “main scale” + “vernier”.
  • Keep units in every line, then give a final answer in cm.

5A. Interactive Trainer

Do this first before the static set

Use the simulation to generate random vernier readings, then use the fixed questions below to lock in exam method.

Simulation Trainer: Vernier Caliper Reading

Train the no-zero-error vernier workflow: main scale, aligned division, final reading in cm.

BetaO LevelA LevelPractical SkillsBest for: O Level and H2 practical preparation
  • Main Scale Reading
  • Vernier Alignment
  • Instrument Precision

Open the full interactive simulation on its own page

Use the standalone simulation page for the live controls, SVG scene, run modes, and scoring flow.

Open Interactive Simulation

The lesson stays lightweight and links out to the dedicated simulation page.

After this trainer
  1. Measurement Quiz
  2. Structured Measurement
  3. Practice: Finding Vernier Zero Error
  4. Practice: Vernier Reading with Zero Error

6. Worked Examples

Modelled example 1

Question 1 — modelled reading

Core

Problem

Read the vernier caliper in centimetres.
Vernier reading question 1Read the scale: the main-scale value immediately left of vernier zero is 8.6 centimetres, and vernier division 2 aligns with a main-scale line.Read the scalemain scale (cm)8.69.6vernier scale0510best alignment
Study the worked solution

  1. Read the main scale

    Method

    The main-scale reading immediately left of vernier zero is 8.6 cm.

    Reason

    The value to the right has not yet been passed.

    Working

    xₘₐᵢₙ = 8.6 cm

  2. Read the vernier

    Method

    Division 2 aligns, giving 0.02 cm.

    Reason

    Each vernier division represents 0.01 cm.

    Working

    xᵥₑᵣₙᵢₑᵣ = 2(0.01) = 0.02 cm

  3. Add the readings

    Method

    The observed reading is 8.62 cm.

    Reason

    The vernier part refines the main-scale reading.

    Working

    x = 8.6 + 0.02 = 8.62 cm

Guided practice 2

Question 2 — zero main-scale contribution

About 3 min

Problem

Read the vernier caliper in centimetres.
Vernier reading question 2Read the scale: the main-scale value immediately left of vernier zero is 0.0 centimetres, and vernier division 6 aligns with a main-scale line.Read the scalemain scale (cm)0.01.0vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

Hints

Hint 1: separate the two scale parts
Write 0.0 cm + 6(0.01 cm).
View solution step by step

  1. Read both parts

    Method

    The main scale is 0.0 cm and division 6 contributes 0.06 cm.

    Reason

    Aligned vernier division n contributes n × 0.01 cm.

    Working

    0.0 + 6(0.01)

  2. State the reading

    Method

    The reading is 0.06 cm.

    Reason

    The zero main-scale contribution does not remove the vernier contribution.

    Working

    x = 0.0 + 0.06 = 0.06 cm

Guided practice 3

Question 3 — combine both scales

About 3 min

Problem

Read the vernier caliper in centimetres.
Vernier reading question 3Read the scale: the main-scale value immediately left of vernier zero is 6.4 centimetres, and vernier division 3 aligns with a main-scale line.Read the scalemain scale (cm)6.47.4vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

Hints

Hint 1: convert division 3
The vernier contribution is 3(0.01 cm).
View solution step by step

  1. Read both parts

    Method

    The main scale is 6.4 cm and the vernier contributes 0.03 cm.

    Reason

    Division 3 is the aligned vernier mark.

    Working

    xᵥₑᵣₙᵢₑᵣ = 3(0.01) = 0.03 cm

  2. Add

    Method

    The reading is 6.43 cm.

    Reason

    Observed reading equals main plus vernier.

    Working

    x = 6.4 + 0.03 = 6.43 cm

Common misconception 4

Question 4 — place-value trap

Find and correct the mistake

Learner claim

A learner reads the scale as 1.60 cm because division 6 aligns. Diagnose the reading.
Vernier reading question 4Read the scale: the main-scale value immediately left of vernier zero is 1.0 centimetres, and vernier division 6 aligns with a main-scale line.Read the scalemain scale (cm)1.02.0vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

View solution step by step

  1. Diagnose the place value

    Method

    Division 6 means 0.06 cm, not 0.60 cm.

    Reason

    The least count is 0.01 cm per vernier division.

    Working

    6(0.01) = 0.06 cm

  2. Correct the reading

    Method

    The observed reading is 1.06 cm.

    Reason

    Add the vernier contribution to the 1.0 cm main scale.

    Working

    x = 1.0 + 0.06 = 1.06 cm

Common misconception 5

Question 5 — choose the main-scale mark on the left

Find and correct the mistake

Learner claim

A learner uses 5.4 cm as the main-scale value and reports 5.41 cm. Diagnose the method.
Vernier reading question 5Read the scale: the main-scale value immediately left of vernier zero is 5.3 centimetres, and vernier division 1 aligns with a main-scale line.Read the scalemain scale (cm)5.36.3vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

View solution step by step

  1. Correct the main scale

    Method

    The main-scale reading is 5.3 cm.

    Reason

    The vernier zero has passed 5.3 cm but not 5.4 cm.

    Working

    xₘₐᵢₙ = 5.3 cm

  2. Add the vernier

    Method

    The reading is 5.31 cm.

    Reason

    Aligned division 1 adds 0.01 cm.

    Working

    x = 5.3 + 1(0.01) = 5.31 cm

Examiner practice 6

Question 6 — examiner working

3 marks

Examination question

Read the vernier caliper in centimetres and show the main-scale and vernier contributions. [3 marks]
Vernier reading question 6Read the scale: the main-scale value immediately left of vernier zero is 3.8 centimetres, and vernier division 3 aligns with a main-scale line.Read the scalemain scale (cm)3.84.8vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

View solution step by step

  1. Main scale

    1 mark

    Method

    3.8 cm.

    Reason

    This is immediately left of vernier zero.

    Working

    xₘₐᵢₙ = 3.8 cm

  2. Vernier

    1 mark

    Method

    0.03 cm.

    Reason

    Division 3 aligns.

    Working

    3(0.01) = 0.03 cm

  3. Total

    1 mark

    Method

    3.83 cm.

    Reason

    Add the two scale contributions.

    Working

    3.8 + 0.03 = 3.83 cm

Examiner practice 7

Question 7 — high aligned division

3 marks

Examination question

Read the vernier caliper in centimetres and show both scale contributions. [3 marks]
Vernier reading question 7Read the scale: the main-scale value immediately left of vernier zero is 4.2 centimetres, and vernier division 7 aligns with a main-scale line.Read the scalemain scale (cm)4.25.2vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

View solution step by step

  1. Resolve the scales

    2 marks

    Method

    The parts are 4.2 cm and 0.07 cm.

    Reason

    Division 7 aligns and each division is 0.01 cm.

    Working

    xᵥₑᵣₙᵢₑᵣ = 7(0.01) = 0.07 cm

  2. Add

    1 mark

    Method

    The reading is 4.27 cm.

    Reason

    Observed reading is main plus vernier.

    Working

    x = 4.2 + 0.07 = 4.27 cm

Examiner practice 8

Question 8 — whole-centimetre main scale

3 marks

Examination question

Read the vernier caliper in centimetres and show both scale contributions. [3 marks]
Vernier reading question 8Read the scale: the main-scale value immediately left of vernier zero is 7.0 centimetres, and vernier division 5 aligns with a main-scale line.Read the scalemain scale (cm)7.08.0vernier scale0510best alignment

Try this before viewing the solution

Unit: cm

View solution step by step

  1. Resolve the scales

    2 marks

    Method

    The parts are 7.0 cm and 0.05 cm.

    Reason

    Division 5 aligns.

    Working

    xᵥₑᵣₙᵢₑᵣ = 5(0.01) = 0.05 cm

  2. Add

    1 mark

    Method

    The reading is 7.05 cm.

    Reason

    The two contributions have different decimal places.

    Working

    x = 7.0 + 0.05 = 7.05 cm

Challenge 9

Question 9 — near-zero reading and unit transfer

Minimal support

Independent transfer

Read the vernier caliper in centimetres, then express the same length in millimetres.
Vernier reading question 9Read the scale: the main-scale value immediately left of vernier zero is 0.2 centimetres, and vernier division 4 aligns with a main-scale line.Read the scalemain scale (cm)0.21.2vernier scale0510best alignment

Try this before viewing the solution

Unit: cm
Unit: mm

Hints

Hint 1: finish the instrument reading first
Calculate 0.2 + 4(0.01) in centimetres before converting units.
View solution step by step

  1. Read the scale

    Method

    The observed reading is 0.24 cm.

    Reason

    The main scale is 0.2 cm and division 4 adds 0.04 cm.

    Working

    x = 0.2 + 4(0.01) = 0.24 cm

  2. Convert the representation

    Method

    The same length is 2.4 mm.

    Reason

    1 cm = 10 mm.

    Working

    0.24 × 10 = 2.4 mm

7. Mind Stretchers

Mind stretcher 1: Convert your answer to SI unitExtension

Convert 8.62 cm to metres.

Show Answer

8.62 cm = 0.0862 m.

Mind stretcher 2: Parallax checkExtension

Why must you read the vernier scale at eye level?

Show Answer

To avoid parallax error: reading at an angle shifts the apparent alignment and gives the wrong vernier division.

Continue with the next resource in this course.

Course and syllabus information
Course
G3 Physics topic extensions
Syllabus scope
Beyond the syllabus
Edition
G3 Physics topic extensions