What is the near point of a normal human eye (in $cm$)?

The figure below shows the refraction of a ray through a prism. Copy the diagram and,ignoring dispersion at the faces $AB$ and $AC$,mark the following angles: $(i)$ The angle of incidence,$(ii)$ the angle of refraction at the face $AB$,$(iii)$ the angle of emergence,and $(iv)$ the angle of deviation.

Which of the following are the primary colours of light?

The clear sky appears blue because

What is the cornea?

When light rays enter the eye,most of the refraction occurs at the