Question

NEAR point of a person is 175
ANALYSE THE ABOVE SENTENCE AND ANSWER THE FOLLOWING QUESTIONS
1 what type of the defect of eye that the person has
2 what type of lens is used to correct that defect of eye
3 find the focal length of the lens
4 what is the power of that lens​

Answer 1

Answer:

1 hypermetropia

concave lens

87.5

-3.8

Answer 2

Defect is hypermetropia. Power of lens is 0.0342 D.

Explanation:

• To find the focal length given information is

             ⇒  v = 25 cm

             ⇒ u = 175 cm

      So,  

                        ⇒  $\frac{1}{f} = \frac{1}{u} + \frac{1}{v}$

                         ⇒ $\frac{1}{f} = \frac{1}{25} - \frac{1}{175}$

                        ⇒ f = 29.166 cm

• Convex lens is used because it is a converging lens.

• The defect is hypermetropia. In hypermetropia person can not see the perfect image from the distance of 25 cm.

• Power of lens,

                                    ⇒  P = $\frac{1}{f}$

                                    ⇒ P = 0.0342 D.