A person wears glasses of power $\mathit{-}\mathit{2}\mathit{.}\mathit{5} \mathrm{D}$. Is the person far-sighted or near-sighted? What is the far point of the person without glasses?

A ray of light passes through a prism as shown in the figure given below: The angle $\delta$ is known as 

At a particular minimum value of angle of deviation, the refracted ray becomes:

Two identical prisms $ABC$ and $A\text{'}B\text{'}C\text{'}$ are given. White light is passed through $ABC$ as shown below: Which of the following positions of $\mathrm{A}\text{'}\mathrm{B}\text{'}\mathrm{C}’$ will again yield white light: