What is the complementary color of green?

The eye defect known as $Presbyopia$ is corrected by using a $........$ lens.

Which optical phenomenon is responsible for the early sunrise and delayed sunset?

$A$ person needs a lens of power $-0.5 \text{ D}$ for correcting his distant vision. For correcting his near vision,he needs a lens of power $+1.5 \text{ D}$. What is the focal length of the lens required for correcting his $(i)$ distant vision,$(ii)$ near vision?

When do we consider a person to be myopic or hypermetropic? Explain using diagrams how the defects associated with myopic and hypermetropic eye can be corrected?

Define dispersion of white light.