Question

A student uses spectacles of focal length - 2.5 m.
Name the defect of vision he is suffering from
Which lens is used for the correction of this defect?
(e) List two main causes of developing this defect
(d) Compute the power of this lens

​

Answer 1

Answer:

Explanation:

f= - 2.5 m

a) Since, the focal length is negative, it is a concave lens and it is used in myopia

b) Concave

C) Elongated eyeballs or decreased focal length due to abnormal curvature

D) power= 1/f

=1/-2.5

= -10/25

= -0.4Dioptre