MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Parts of an Eye

A person uses...

Question

A person uses concave lenses, if he sees after removing its spectacles, then in his eyes image ofthe object will be formed

A

Behind retina

No worries! We‘ve got your back. Try BYJU‘S free classes today!

B

On fovea centralis

No worries! We‘ve got your back. Try BYJU‘S free classes today!

C

In front of retina

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

D

Far from retina

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is C In front of retina
The lens capsule is attached to the ciliary body by a ligament and serves to refract and focus light rays on retina and fovea centralis. This makes option B incorrect as if the image is focused on fovea centralis, the person would not need to wear lens. The convex lens bends the light rays and help focus the image on the retina which was otherwise being focused behind the retina or far from the retina by a less flexible lens or shortened eye ball; options A and D are incorrect. If the image was being focused in front of retina, as is the condition in myopia caused by elongated eyeball, the person would need a concave lens to diverge the light rays and thereby focus the image on the retina. This makes option C correct.

Suggest Corrections

thumbs-up

0

Similar questions

Q. A person is wearing spectacles with concave lenses for correcting vision. While not using the glasses, the image of a distant object in his case will be formed

Q. A person cannot see distant objects clearly. His vision can be corrected by using the spectacles containing :
(a) concave lenses (b) plane lenses (c) contact lenses (d) convex lenses

Q. A person wears a pair of spectacles with a concave lens of power -2D. Find the farthest point to which he can see objects distinctly without his spectacles.

Q. The ciliary muscles of eye control the curvature of the lens in the eye and hence and alter the effective focal length of the system. When the muscles are fully relaxed, the focal length is maximum. When the muscles are strained, the curvature of lens increases. That means, radius of curvature decreases and focal length decreases. For a clear vision, the image must be on the retina. The image distance is therefore fixed for clear vision and it equals the distance of retina from eye lens. It is about

25 c m

for a grown up person.
A person can theoretically have clear vision of an object situated at any large distance from the eye. The smallest distance at which a person can clearly see is related to minimum possible focal length. The ciliary muscles are most strained in this position. For an average grown up person, minimum distance of the object should be around

25 c m

.
A person suffering from eye defects uses spectacles (eye glass). The function of lens of spectacles is to form the image of the objects within the range in which the person can see clearly. The image of the spectacle lens becomes object for the eye lens and whose image is formed on the retina.
The number of spectacle lens used for the remedy of eye defect is decided by the power of the lens required and the number of spectacle lens is equal to the numerical value of the power of lens with sign. For example, if power of the lens required is

+ 3 D

(converging lens of focal length

100 / 3 c m

), then number of lens will be

+ 3

.
For all the calculations required, you can used the lens formula and lensmaker's formula. Assume that the eye lens is equiconvex lens. Neglect the distance between the eye lens and the spectacle lens.
A far sighted man cannot see objects clearly unless they are at least

100 c m

from his eyes. The number of the spectacle lenses that will make his range of clear vision equal to an average grown up person will be

Q. The eye forms a real and inverted image of an object on the retina. If the eye lens is defective, the image of objects may be formed in front of or behind the retina. Persons in whom the image is formed in front of the retina are not able to see the distant objects clearly while if the image is formed behind the retina the person is not able to see a near object clearly. The latter kind of people is said to be longsighted.
Persons suffering from myopia cannot see clearly the

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Parts of an eye

BIOLOGY

Watch in App

explore_more_icon

Explore more

Parts of an Eye

Standard IX Biology

Join BYJU'S Learning Program

CrossIcon