Micrometer, << my KROM uh tuhr, >> is a mechanical device that measures small distances or angles. The term micrometer comes from Greek words meaning small measure, and micrometers are used for precision measurement. A wide variety of scientific and engineering instruments are equipped with micrometers, including telescopes, microscopes, and surveying tools.
A commonly used micrometer called a micrometer caliper measures the thickness of objects. It consists of a micrometer spindle or screw that turns inside a fixed nut. The nut is covered by a sleeve. The spindle can be closed on the object to be measured by rotating a part called the thimble. The number of turns made by the thimble is measured by two scales, one on the sleeve and the other on the thimble. In many metric micrometers, each rotation of the thimble advances the spindle 0.5 millimeter on the linear scale. The circular scale on the thimble can measure to 1/50 of 0.5 millimeter, or 0.01 millimeter.
