Mr Hassan’s Vernier Callipers Lab

Main scale first. Then find the vernier tick that best aligns.

APPARATUS: 10-DIV VERNIER (LEAST COUNT 0.1 mm)
RANGE: 0–50.0 mm (0–5.0 cm)

Vernier has no numbers. The longest ticks are 0, 5, and 10.

If the instrument reads 0.0 mm when closed, no correction is needed.

12.4 mm

How to read

  1. Main scale (in the window): read the last whole mm to the left of the vernier zero.
  2. Vernier scale (on the slider): find the one tick that best aligns with a main-scale tick.
  3. Add: main + (vernier index × 0.1 mm).

Practical precautions (AQA-style)

  • Zero error: close the jaws gently and check alignment; correct every reading if needed.
  • Technique: use the thumb-wheel/fine adjust (if present) rather than shoving the slider; avoid crushing soft objects.
  • Square contact: keep jaws at right angles to the object; don’t measure on a skew.
  • Parallax: read straight-on; your eye should be perpendicular to the scale window.
  • Repeat: take multiple readings; for cylinders, rotate and re-measure.
  • Cleanliness: wipe jaws before measuring (tiny grit = big error).

Engraving variation

  • The tick marks have a tiny variation in darkness/length, to feel more like a real instrument.
  • It is deterministic: nothing “wiggles” when you move the slider.