question_answer 35)

  A person needs a lens of power -4.5 D for correction of her vision. (a) What kind of defect in vision is she suffering from? (b) What is the focal length of the corrective lens?                 (c) What is the nature of the corrective lens?

Answer:

                  (A) As the power of lens is negative, she must be suffering from myopia. (b) Power, P = -4.5 D, focal length, f = ? m =cm (c) The nature of the corrective lens is concave or divergent.