Which kind of lens is used to correct long-sightedness (hypermetropia)?

A ......... lens is used to correct presbyopia.

Which of the following is true for near sightedness?

Which of the following is true for far- sightedness?

What kind of diode is used as a photo detector?

A ......... corrective lens is used to rectify near-sightedness.

Give scientific reasons for the following statements: To rectify the defect of far-sightedness or hypermetropia, convex lens of suitable focal length is used as corrective lens.

Which lens is used by a person suffering from far-sightedness?