Every colour travels with the same speed in a transparent medium.

How is long-sightedness corrected?

What is meant by the near point of the eye?

When white light is incident on a blue pigment,which colors of light are reflected?

Study the diagram and answer the questions that follow:
$(i)$ Identify the defect of vision represented by this diagram.
$(ii)$ List the two possible causes of this defect.
$(iii)$ With the help of a ray diagram,explain how this defect can be corrected.

Due to atmospheric refraction, the sun is visible about $2$ minutes before the actual sunrise and about $2$ minutes after the actual sunset. By how much time is the day lengthened due to this phenomenon?