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Measurement & Vectors · Physics

Screw Gauge (Micrometer) Simulation

Turn the thimble of a screw gauge to grip a wire and read it: main-scale reading plus circular-scale divisions × least count, corrected for zero error. Then solve practice readings.

Interactive virtual lab · no download · works on phones and laptops

Chapter
Units and Measurements
For
Class 11 · JEE · NEET
Time
~12 min

How to use it

  1. 1Drag the thimble (or use the arrows) to open and close the jaws.
  2. 2Place a wire or ball between the jaws and close until it grips.
  3. 3Change pitch, divisions and zero error in the panel.
  4. 4Practice: read the gauge and type your answer.

What to notice

  • Least count = pitch ÷ number of circular-scale divisions.
  • Reading = MSR + (CSR × LC) − zero error.
  • A positive zero error means the zero of the circular scale is below the line: subtract it.
  • Always turn the ratchet, not the thimble, to avoid over-tightening.

For teachers

Teach it in 21 minutes

A lesson plan, questions to put to the class, a quick quiz you can project or print, and the formulas behind Screw Gauge (Micrometer).

  1. 1Hook

    ~2 min
    • Hold up a thin wire and ask: “Your ruler reads to 1 mm. How could you measure this to a hundredth of a millimetre?” Let them guess, then open the screw gauge.

  2. 2Demonstrate

    ~7 min
    • Drag the thimble (or use the arrows) to open and close the jaws.
    • Place a wire or ball between the jaws and close until it grips.
    • Change pitch, divisions and zero error in the panel.
    • Practice: read the gauge and type your answer.

  3. 3Pause and ask

    ~5 min
    • Have a student say this in their own words: Least count = pitch ÷ number of circular-scale divisions.
    • Have a student say this in their own words: Reading = MSR + (CSR × LC) − zero error.
    • Have a student say this in their own words: A positive zero error means the zero of the circular scale is below the line: subtract it.
    • Have a student say this in their own words: Always turn the ratchet, not the thimble, to avoid over-tightening.

  4. 4Check

    ~7 min
    • Run the 7-question quiz below: project it and take answers by show of fingers (1–4), or print it as a worksheet.

About the Screw Gauge (Micrometer) simulation

A screw gauge (micrometer) measures small lengths, like the diameter of a wire, to a hundredth of a millimetre. Each full turn of the thimble moves the spindle by one pitch; the circular scale divides that turn into equal parts, so its least count is the pitch divided by the number of divisions.

This screw gauge simulation lets you turn the thimble, grip a wire or ball, read the main scale and circular scale, and correct for positive or negative zero error. Practice mode gives you readings to solve. It covers Units and Measurements in Class 11, the screw gauge practical, and the reading questions in JEE Main and NEET.

Also covers: micrometer screw gauge, least count, pitch, zero error, main scale, circular scale, units and measurement.

Frequently asked questions

What is the least count of a screw gauge with 0.5 mm pitch and 50 divisions?

0.5 / 50 = 0.01 mm.

How do you correct for zero error?

Subtract it (with its sign): a positive zero error is subtracted from the reading, a negative one is effectively added.

Why use the ratchet instead of the thimble to close the gauge?

The ratchet slips at a fixed pressure, so you don't squash the wire or strain the screw.

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