question_answer 18)

  A person cannot see distinctly objects kept beyond 2 m. This defect can be corrected by using a lens of power (a) +0.5 D                             (b) -0.5 D                             (c) +0.2 D                             (d) -0.2 D

Answer:

                    (B) As the person has the eye defect, myopia, therefore, a concave lens has to be used whose focal length will be, f = -2 m (using sign convention). Thus, Power, (where,  f is focal length in metre) D