Paper 2 · Reading a micrometer screw gauge
A micrometer screw gauge is used to measure the diameter of a small workpiece. Which of the following is a correct precaution to take when using this instrument?
AUse the ratchet to avoid over-tightening on the workpiece.
BTighten the thimble as hard as possible to get a firm grip.
CImmerse the jaws in water after each measurement to keep them clean.
DLeave the jaws fully closed and store the instrument in direct sunlight.
Explanation: The ratchet lets the user apply a consistent, gentle force and stops over-tightening, which would damage the instrument or crush the workpiece. Over-tightening, wetting the jaws, and sunlight storage are all poor practice.
Derived from ZIMSEC Physics 5055/2 Paper 2 Theory, November 2017, Q1
