How are we able to see nearby and also the distant objects clearly?

What is the eye lens made of?

In the dispersion of white light by a prism,which color of light undergoes the maximum deviation?

$A$ student finds the writing on the blackboard blurred and unclear while sitting on the last desk in a classroom. He,however,sees it clearly while sitting on the front desk at about $2\, m$ from the blackboard.
$(a)$ Draw ray diagrams to illustrate the formation of image of the blackboard writing by his eye lens when he is seated at the $(i)$ last desk,$(ii)$ front desk.
$(b)$ Name the defect of the eye from which the student is suffering.
$(c)$ Name the kind of lens that would help him to see clearly even when he is seated at the last desk. Draw a ray diagram to illustrate how this lens helps him to see clearly.

Sometimes you see a person reading the newspaper by placing it far away from their eyes. Which defect is the person suffering from? How can this defect be corrected?

Give one cause of long-sightedness (hypermetropia).