What is the pitch of vernier callipers?

Hint: Vernier scale is defined as a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation,therefore increasing resolution and reducing measurement uncertainty by using vernier acuity to reduce human estimation error.

Complete answer:
Single measured value pointer is replaced by a vernier scale and has for instance ten divisions equals in distance to nine divisions on the main scale .the interpolated reading which can be obtained by observing which of the vernier scale graduation is coincident with a graduations on the main scale,which can be easier to perceive than visual estimation between two points and such kind of arrangement can go to a higher resolution by using a higher scale ratio known as the vernier constant.
Pitch which can be defined as the distance travelled by the spindle per revolution which is measured by moving head scale over the pitch scale.
In vernier calipers there is no rotating screw , therefore ,there is no pitch pitch for vernier calipers.

Note: A vernier are used in used on circular or straight scales where a simple linear mechanism is adequate and the name ‘vernier’ was popularized by the French astronomer Jerome lalande through his traité d'astronomie.vernier scale is called a nonius after Portuguese mathematician and calipers are the most typical use of vernier scales today.