Question

defect in the eye if a person cannot see objects distinctly within 50 cm. Normal eye can see within 25 cm

Answer 1

Answer

Given,

The person is suffering from a disorder of eye called Hypermetropia in which a person can't see the nearby objects clearly.

Hypermetropia is also called far sightedness.

It can be fixed by using a convex lens of proper power.

Now, according to the question=>

u(object distance) = -25cm

v(image distance) = -50cm.

now, by using lens formula=>

1/v - 1/u = 1/f

=>-1/50 +1/25 = 1/f

=>2-1/50 = 1/f

=>f = 50cm

=>f = +0.5m.

Now, We know that=>

Power = 1/f(in metre)

=>P = 1/0.5

=>P =+ 2 dioptre.

Hence the person should use a convex lens of +2D power.

Answer 2

As 25 cm is the least distinct length of which normal human eyes can see clearly, if a person is having difficulty in seeing objects withing 50cm, he have hypermetropic eyes or he is farsighted.