What is the range of vision for a normal human eye?

What is the far point of a normal human eye?

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

$A$ person is able to see objects clearly only when these are lying at distances between $50\, cm$ and $300\, cm$ from his eye.
$(a)$ What kind of defect of vision is he suffering from?
$(b)$ What kind of lenses will be required to increase his range of vision from $25\, cm$ to infinity? Explain.

Explain the refraction of light through a triangular glass prism using a labelled ray diagram. Hence,define the angle of deviation.

The focal length of the eye lens increases when eye muscles