A person needs a lens of power - 2.5 dioptres for correcting his vision. Name the defect of vision he is suffering from. Which lens will he be using for the correction? Also, find the focal length of lens.
The person is using a concave lens of power - 2.5 D. The person is, therefore, suffering from myopia. He is using a concave lens for correction of eye.
Since P = 1//, therefore, / = 1/P = 1/ 2.5 = 0.4 m = 40 cm