Which tool is used to measure the outside dimensions of an object with high precision?

• A. Steel tape measure
• B. Feeler gauge
• C. Micrometer
• D. Utility knife

Answer: (C)

For high-precision outside dimensions, a micrometer is the instrument of choice. An outside micrometer clamps the object between a fixed anvil and a movable spindle; as you rotate the thimble, the screw advances the spindle a very small, controlled distance. The sleeve scale gives the main measurement, and the thimble provides the precise fraction, giving readings typically to thousandths of an inch (or hundredths of a millimeter). This setup is specifically designed for accurate outside measurements of small parts, such as diameters or thicknesses.

Steel tape measures are meant for longer lengths and lack the fine resolution needed for precise outer dimensions. A feeler gauge uses leaves of different thickness to check clearances, not to measure an outer dimension with high precision. A utility knife is a cutting tool, not a measuring instrument.