Question

A person uses lenses of +2.0 D power in his spectacles for the correction of his vision.

1. Name the defect of vision the person is suffering from.
2. List two causes of this effect.
3. Determine the focal length of the lenses used in the spectacles.

Answer 1

a. Hypermetropia

b.

1. The Focal length of the eye lens has increased.
2. The distance between the eye lens and the retina has decreased.

c. P = +2 D

f = `1/P`

= `1/2`

= +0.5 m