wiz-icon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

The near-point of a hypermetropic eye is 75 cm from the eye. What is the power of the lens required to enable the person to read a book held at 25 cm from the eye?

A
+3 D
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
2.5 D
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
+2.66 D
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
2.66 D
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C +2.66 D
The near point of a normal human being is 25 cm. Therefore, to correct a hypermetropic person capable of seeing things only 75 cm away from the eyes, we need a corrective lens that forms the image at 75 cm of the object which is kept between 25 to 75 cm.

Focal length of convex lens to be used can be found by the lens formula:
1v1u=1f
where f is the focal length and u, v are the object and image distance respectively.
Here u=25 cm=14 mv=75 cm=34 m

1f=1(34)1(14)

=43(4)1=83

We know that,
Power, P=1f=83=2.66 D
So the person needs a convex lens of power +2.66 D.

flag
Suggest Corrections
thumbs-up
1
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Power of Accommodation and Defects
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon