(i) Identify the type of lenses used in her spectacles. (ii) Identify the defect of vision Surabhi is suffering from.

Question

Surabhi from Std. X uses spectacles. The power of the lenses in her spectacles is 0.5 D.

(i) Identify the type of lenses used in her spectacles.

(ii) Identify the defect of vision Surabhi is suffering from.

(iii) Find the focal length of the lenses used in her spectacles.

Answer 1

(i) Convex lenses are used in the spectacles used by Surabhi.

(ii) Surabhi is suffering from hypermetropia (farsightedness).

(iii) Focal length of the lenses used in her spectacles = \(\frac{1}{power\,of\,the\,lens}=\frac{1}{0.5\,D}\) = 2 m.