A screw gauge has main scale divisions of $1 \mathrm{mm}$ each and its circular scale has $100$ divisions while measuring a diameter of a wire, cap end is after ${21}^{\mathrm{st}}$ marking of main scale and ${52}^{\mathrm{nd}}$ division of circular scale coincides with the reference line, what is the measured diameter of the wire

The figure shows a situation when jaws of vernier are touching each other one main scale division is of $1 \mathrm{mm}$. The zero correction in reading measured will be

The reading of micrometer screw gauge shown in figure (Least count is $0.01 \mathrm{mm})$

Graph of position of image $\left(v\right)$ versus position of point object $\left(u\right)$ from a convex lens is shown. The focal length of the lens in $\left(\mathrm{cm}\right)$ is (Least count of scale is $0.1 \mathrm{cm}$)