Question

Near point of a person is 50 cm. In order to get normal vision what kind of specticals should he use​

Answer 1

Explanation:

So first of all, let's see the basic overview of two kinds of eye vision imparities, Myopia and Hypermetropia.

MYOPIA:

• People not able to see distant objects clearly.
• But he can see the nearby objects.
• The far point becomes closer to infinity and near point remains normal.
• Due to increase in size of eyeball or decrease in focal length of eye lens.
• Image formed Infront of retina.
• Can be corrected by Diverging(Concave) lens.

✏️ Refer to the attachment.....

HYPERMETROPIA:

• People not able to see nearby objects clearly.
• But he can see distant objects.
• The near point becomes greater than 25 cm but the far point remains normal.
• Due to decrease in size of eyeball or increase in focal length of eye lens.
• Image formed behind the retina.
• Can be corrected by Converging (Convex) lens.

✏️ Refer to the attachment......

Back to the Question:

The near point of the person's eye is 50 cm which greater than normal near point of 25 cm. So, we can say that he is suffering from Hypermetropia. This can be corrected by using the:

$\LARGE{ \boxed{ \bf{ \purple{Convex \: lens}}}}$

With suitable power according to the defect. And we are done !!

━━━━━━━━━━━━━━━━━━━━

Answer 2

$\huge{\underline{\underline{\boxed{\sf{\purple{Answer ࿐}}}}}}$

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

• Concave lens of focal length 50 cm.

• The near point of an elderly person = 50cm from the eye.

• For minimum to see object placed at normal point, its image should be formed 50 cm from the eye.

━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━