Give one cause of near-sightedness (myopia).

$(i)$ What is the least distance of distinct vision for a normal eye?
$(ii)$ Does the above distance increase or decrease for a long-sighted eye (hypermetropia)? Give a reason for your answer with a diagram.

$(i)$ Calculate the maximum power of accommodation of a person having normal vision.
$(ii)$ $A$ person needs to use glasses for reading a newspaper. Identify the defect in her vision and the type of lens she would need to correct it.
$(iii)$ Sometimes when we enter a dark room from bright sunlight,we are unable to see objects clearly. Why?

When a beam of white light is passed through a prism,violet colour bends the most and red colour the least.

Explain the following terms connected with the eye:
$(i)$ Ciliary muscles
$(ii)$ Accommodation
$(iii)$ Blind spot.

If the size of the scattering particles is large,which color of light do they scatter?