The image for the converging beam after refraction through the curved surface (in the given figure) is formed at:

In the figure $\left(i\right)$ a thin lens of focal length $10 \mathrm{cm}$ is shown. The lens is cut into two equal parts, and the parts are arranged as shown in the figure $\left(ii\right)$. An object $AB$ of height $1 \mathrm{cm}$ is placed at distance of $7.5 \mathrm{cm}$ from the arrangement. The height of the final image will be:

Diameter of a plano-convex lens is $6 \mathrm{cm}$ and thickness at the centre is $3 \mathrm{mm}$. If speed of light in material of lens is $2\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1}$ the focal length of the lens is (Speed of light in vacuum = $3\times {10}^8 \mathrm{m} {\mathrm{s}}^{-1})$