Abnormalities in the normal vision of the eye are called defects of vision.

What is the lens-like structure present in the eye called?

$(a)$ Demonstrate an activity with a well-labelled diagram to prove that white light is made up of seven colours.
$(b)$ Which colour of light bends least and which one the most while passing out from the prism? Also,state the reason for the same.

$A$ person cannot see objects farther than $12\, m$ from the eye clearly. Name the defect of vision he is suffering from and the lens that should be used for correction of this defect. Illustrate with the help of a diagram,how this lens will correct the defective vision?

What is the complementary color of blue?

Presbyopia is a type of far-sightedness.