Using screw gauge of pitch $0.1$ $cm$ and $50$ divisions on its circular scale, the thickness of an object is measured. It should correctly be recorded as 

The pitch and the number of divisions, on the circular scale, for a given screw gauge are $0.5\,mm$ and $100$ respectively. When the screw gauge is fully tightened without any object, the zero of its circular scale lies $3$ divisions below the mean line. The readings of the main scale and the circular scale for a thin sheet, are $5.5\,mm$ and $48$ respectively, the thickness of this sheet is

In an experiment with Vernier callipers of least count $0.1\,mm$, when two jaws are joined together the zero of Vernier scale lies right to the zero of the main scale and $6^{\text {th }}$ division of Vernier scale coincides with the main scale division. While measuring the diameter of a spherical bob, the zero of vernier scale lies in between $3.2\,cm$ and $3.3\,cm$ marks, and $4^{\text {th }}$ division of vernier scale coincides with the main scale division. The diameter of bob is measured as $…….\,cm$

A spectrometer gives the following reading when used to measure the angle of a prism. 

Main scale reading : $58.5$ degree

Vernier scale reading : $09$ divisions

Given that $1$ division on main scale corresponds to $0 .5$ degree. Total divisions on the Vernier scale is $30$ and match with $29$ divisions of the main scale. The angle of the prism from the above data ……. $degree$