A person uses lenses of +2.0 D power in his spectacles for the correction of his vision. (a) Name the defect…
A person uses lenses of +2.0 D power in his spectacles for the correction of his vision.
(a) Name the defect of vision the person is suffering from.
(b) List two causes of this defect.
(c) Determine the focal length of the lenses used in the spectacles.
Solution
(a) Hypermetropia
(b) Two causes:
Eye ball has become too small /Eye ball is shortened
The focal length of the eye Lens is long / eye lens becomes less convergent
(c) Focal length = $\dfrac{1}{P}$ = 1/2 = + 0.5 m