Using a Micrometer (Edexcel International A Level (IAL) Physics): Revision Note

Using a Micrometer

• A micrometer, or a micrometer screw gauge, is a tool used for measuring small widths, thicknesses or diameters

  • For example, the diameter of a copper wire

• It has a resolution of 0.01 mm

• The micrometer is made up of two scales:

  • The main scale - this is on the sleeve (sometimes called the barrel)

  • The thimble scale - this is a rotating scale on the thimble

Components of a micrometer

• The spindle and anvil are clamped around the object being measured by rotating the ratchet

  • This should be tight enough so the object does not fall out but not so tight that it is deformed

  • Never tighten the spindle using the barrel, only using the ratchet. This will reduce the chances of overtightening and zero errors

• The value measured from the micrometer is read where the thimble scale aligns with the main scale

  • This should always be recorded to 2 decimal places (e.g. 1.40 mm not just 1.4 mm)

The micrometer reading is read when the thimble scale aligns with the main scale