Question

Why is the normal eye unable to focus on an object placed within 10 cm from the eye?

Answer 1

Because human eye can see a object placed at a distance of 25cm. If object placed with 25cm then the image of the object formed behind the retina then object seems blurred.

Answer 2

This is because the near point of a normal eye is 25 cm.

Explanation:

Near point of eye

This is the nearest distance up to which a normal can see a near by object very clearly. The object closer to this will not appear clear , it appears blur.

That is why a person with normal vision cannot see an object at the distance of 10 cm clearly.