The graph between angle of deviation $\left(\mathrm{\delta }\right)$ and angle of incidence $\left(i\right)$ for a triangular prism is represented by: 

Monochromatic light is incident on a glass prism of angle $\mathrm{A}$. If the refractive index of the material of the prism is $\mathrm{\mu }$, a ray, incident at an angle $\mathrm{\theta }$, on the face $\mathrm{AB}$ would get transmitted through the face $\mathrm{AC}$ of the prism provided.

A U-shaped wire is placed before a concave mirror having radius of curvature $20 \mathrm{cm}$ as shown in the figure. Find the total length of the image.

(i) A paperweight of refractive index $n=\frac{3}{2}$ in the form of a hemisphere of the radius $3.0 \mathrm{cm}$ is used to hold down a printed page. An observer looks at the page vertically through the paperweight. At what height above the page will the printed letters near the centre appear to the observer? (ii) Solve the previous problem if the paperweight is inverted at its place so that the spherical surface touches the paper.