The Vernier Scale
The Vernier Scale is a very useful scale to use as it allows the measurement of a length or distance to be measured as accurately as ±0.01mm. The scale is used extensively within the Waves sub-unit, when measuring fringe separation in interference patterns for example.
The video below shows a guide to reading a Vernier Scale:-
Below is some example Vernier Scales (each division = 0.1mm), with the correct measurements shown:-
Vernier Calipers comprise a calibrated scale with a fixed jaw, and another jaw, with a pointer, that slides along the scale. The distance between the jaws is then read using the Vernier scale.
Below is some example Vernier Calipers (each scale division = 0.02mm), with the correct measurements shown:-
The Micrometer is another device that use can be used to make very accurate measurements of a length or distance. Micrometers use a screw to transform small distances (that are too small to measure directly) into large rotations of the screw that are big enough to read from a scale.
The video below shows a guide to reading a Micrometer:-
Below is some example Micrometers (each scale division = 0.01mm), with the correct measurements shown:-