Vernier Callipers and Screw Gauge

Also called

vernier callipers · vernier calliper · vernier scale · screw gauge · micrometer screw gauge · least count · zero error · pitch · circular scale · main scale · coinciding division · measurement · precision · significant figures · diameter of a sphere · diameter of a wire · वर्नियर कैलिपर्स · स्क्रू गेज · अल्पतमांक

Topics

• The vernier scale has 10 divisions over 9 mm of the main scale, so one vernier division is 0.9 mm.
• Least count of the callipers = 1 main scale division − 1 vernier division = 1 mm − 0.9 mm = 0.1 mm = 0.01 cm.
• Reading = main scale reading just before the vernier zero + (coinciding vernier division × least count).
• Here the vernier zero lies past 2.3 cm and the 7th vernier line coincides: 2.3 cm + 7 × 0.01 cm = 2.37 cm.
• A screw gauge has a pitch of 1 mm: one full turn of the thimble moves the spindle 1 mm along the sleeve scale.
• With 100 divisions on the circular scale its least count is pitch ÷ divisions = 1 mm ÷ 100 = 0.01 mm.
• If the thimble zero does not meet the reference line when the gauge is closed, the gauge has a zero error.
• Zero error is subtracted from every reading: a positive error (zero below the line) makes readings too large.
• Least count is the smallest length an instrument can measure; a smaller least count means a more precise reading.

About this model

A GLB file of about 339 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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