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Why is normal eye not able to see clearly the objects placed closerthan 25 cms?


Posted- 2263 days ago
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a normal human eye can c objects between 25cm and infinity...this is possible becoz of the ciliary muscles......the ciliary muscle change the size of the eye lens which is made up of a jelly like substance whose focal lenght and power can be changed by changing its thickness.....this is done by the ciliary muscles...........but there is a certain limit till which the ciliary muscles can relax or contract......therefore the  normal human eye can't c objects placed closer dan 25cm......b'coz the max power of the eye is not enough for forming its image on the retina................

 

the ability of the human eye to adjust its focal lenght (power of accomodation) enables it to see both nearby as well as distant objects clearly. But the eye can adjust its focal length upto a ceratin xtent only and hence are range of vision is fixed. Our eyes can focus the image of objects placed less than 25 cm from our eyes and hence we cant see those objects clearly.

 

because eye lens is not able to converge rays on retina.

 

because if object is placed closer than 25 cm than eye lens will not be able converge rays on retina

 

 

a normal human eye can c objects between 25cm and infinity...this is possible becoz of the ciliary muscles......the ciliary muscle change the size of the eye lens which is made up of a jelly like substance whose focal lenght and power can be changed by changing its thickness.....this is done by the ciliary muscles...........but there is a certain limit till which the ciliary muscles can relax or contract......therefore the  normal human eye can't c objects placed closer dan 25cm......b'coz the max power of the eye is not enough for forming its image on the retina................

 

the near point of a normal human eye is 25cm,so our eyes cannot focus clearly on the objects near than 25cm

 

 

Our eye has an ability to contract our relax which is due to ciliary muscles. they halp to adjust the focal length. this is called power of accomodation. ciliary muscles can contract to a certain limeit. ie 25cm and for relaxed it is infinity.

 

it is becoz there is some limit of the eye to adjust its focal length i.e power of accomodation.so the lens can be adjusted to some xtnt only and thus near pnt of normal eye is 25cm..

 

 

the eye can see objects placed at different distances because of the ciliary muscles. these muscles change the shape and size of the eye lens due to which the focal length of the lens is changed. the ciliary muscles are not capable of reducing the focal length below 25 cm. so we cannot see objects placed closer than 25 cm clearly or without causing strain to our eyes.

this is also the reason why 25 cm is called the least distance of distinct vision.

 

we cannot see because the focal length of the eye lens cannot be decreased below a certain minimum limit and the image will appear blurred

 
least distance of proper vision
 

due to least distance

 

the ability of the human eye to adjust its focal lenght (power of accomodation) enables it to see both nearby as well as distant objects clearly. But the eye can adjust its focal length upto a ceratin xtent only and hence are range of vision is fixed. Our eyes can focus the image of objects placed less than 25 cm from our eyes and hence we cant see those objects clearly.

 

Bco'z the focal length of the eye is not decreases less than 25cm.It takes much more strain to see the objects placed at less than 25cm.

 

the eye can see objects placed at different distances because of the ciliary muscles. these muscles change the shape and size of the eye lens due to which the focal length of the lens is changed. the ciliary muscles are not capable of reducing the focal length below 25 cm. so we cannot see objects placed closer than 25 cm clearly or without causing strain to our eyes.

this is also the reason why 25 cm is called the least distance of distinct vision.

 

a normal can human eye can accomodate its eyes upto least distance of vision.

 
Because the least distance of distinct vision of the eye is 25 cms.
 

IT IS SO BECAUSE 25CM IS THE LEAST DISTANCE OF DISTINCT VISION AND OUR CILLIARY MUSCELES DO NOT HAVE THAT MUCH CAPABILITY TO CONTRACT BELOW A CERTAIN LIMIT I.E. 25CM WITHOUT ANY STRAIN. 

 

because eye lens is not able to converge rays on retina.

 

A normal eye can c objects between 25cm to infinity. When an object is placed within 25cm, the ciliary muscles cannot bulge any more. Therefore, objects appear blurred.

 

the range of vision of a normal human eye is only from 25cm to infinity. it, hence, can't see things closer than 25cm from it. this is because the ciliary muscles can't stress further to reduce the focal length of the eye lens.

 

the range of vision for normal eye is frm 25cms to infinity dats y we cannot see object within 25cms

 

because focal length cann't be reduced more than it

 

because normal eye can accomodate its focal lenght upto least distance of distinct vision.

 

IT IS BCOZ CILLIARY MUSCLES CANNOT CONTRACT TO SUCH EXTENT  THAT EYE LENS WILL BE ABLE TO CONVERGE EXTREMELY DIVERGING RAYS COMING FROM OBJECTS PLACED CLOSER THAN 25 CM.

 

its bcoz the least distance of distinct vision is 25cm.thus the eye can see only objects placed at a distance gr8r than 25cm