Question

If your eye glass have focal length 60cm.What is your nor point?

Answer 1

Answer:

between 25 cm and 60 cm=42.85

Step-by-step explanation:

This question shows that it is convex lens which is used by patients of hypermetrophic eye.The near point of normal eye is 25 cm.So he has no problem in seeing near objects but he has problem in seeing far objects.So, It is between 25 cm and 60 cm.

Let us assume that the near point of a normal eye is 25 cm.

Now, any object placed in front of the lens will have its image formed at the near point of the eye.

Thus u = -25cm

v =?

f = 60cm

Now,

1/v -1/u = 1/f

=>1/v +1/25cm = 1/60cm

=>1/v = 1/60cm -1/25cm

=>1/v = -7/300cm

=>v = -300/7 cm ≈ -42.85cm

Thus, the near point of the eye is 42.85cm.

Answer 2

Explanation:

This will surely help you.