Vernier Calipers and Screw Gauge

In a vernier callipers, the least count of main scale is $1 \mathrm{mm}.$ $20$ division of vernier scale are matching with $19$ divisions of main scale. The thickness of the object measured by the vernier callipers will be :

The main scale division and pitch of a screw gauge is $0.05 \mathrm{cm}$. Number of circular scale division in the circular scale is $100$. When no object is placed between the studs then the $0$ of main scale is not visible and $5^{\mathrm{th}}$ division of circular scale coincides with the main scale. When a wire is placed in between the studs then the reading on main scale is $4.6 \mathrm{mm}$ and ${52}^{\mathrm{nd}}$ division on circular scale matches with reference line on main scale. The actual diameter of wire is

A spectrometer gives the following reading when used to measure the angle of the prism:
main scale reading $=58.5$ degree, vernier scale reading $=9$ division. Given that one division on main scale corresponds to $0.5$ degree, $30$ division of vernier scale matches with $29$ division of main scale. The angle of prism from above data:

The least count of the main scale of a vernier callipers is $0.5 \mathrm{mm}$ and the least count of the vernier callipers itself is $0.005 \mathrm{cm}$. Then the number of division on vernier scale is

The circular scale of a screw gauge has $50$ divisions and a pitch of $0.5 \mathrm{mm}$. Find the diameter of the sphere. The main scale reading is $2 \text{mm}$.