Which of the following phenomena is $NOT$ involved in the formation of a rainbow?

How is long-sightedness corrected?

Study the diagram given below and answer the questions that follow it.
$(i)$ Identify the defect of vision represented in this case. Give a reason for your answer.
$(ii)$ Mention the two causes of this defect.

$A$ person cannot see distinctly objects kept beyond $2\, m$. This defect can be corrected by using a lens of power:

Which of the following statements is correct?

To correct astigmatism,we use a cylindrical lens.