Which liquid fills the space behind the cornea?

Which optical phenomenon is responsible for the formation of a rainbow?

Explain why,when the sun is overhead at noon,it appears white?

Which scientist established that white light is composed of seven constituent colors?

What happens to the lens and the ciliary muscles when you are looking at distant objects?

$A$ person can see distant sign boards clearly but cannot read clearly a book which is at $25\, cm$ from his eye. Giving reason,identify the defect. Draw a labelled ray diagram to illustrate this defect and its correction.