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Anupam Dalmia Grade:
        

What are defects of lens????


spherical abrasion and chromatic abration

6 years ago

Answers : (1)

SAGAR SINGH - IIT DELHI
879 Points
										

Dear student,


Lens Defects


 









Chromatic aberration: Image of a white object is coloured and blurred because µ (hence f) of lens is different for different colours. This defect is called chromatic aberration.

 

µv > µR so fR > fV


 

Mathematically chromatic aberration = fR – fv = ωfy


 

ω = Dispersive power of lens.


 

fy = Focal length for mean colour √fRfv


Lens Defects

 

 

Removal: To remove this defect i.e. for Achromatism we use two or more lenses in contact in place of single lens.


 

Mathematically condition of Achromatism is : ω1/f1 + ω2/f2 = 0


 

or     ω1f2 = –ω2f1


 








Spherical aberration:

Inability of a lens to form the point image of a point object on the axis is called Spherical aberration.


 

In this defect all the rays passing through a lens are not focused at a single point and the image of a point object on the axis is blurred.




















Please feel free to ask your queries here. We are all IITians and here to help you in your IIT JEE preparation.


All the best.


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Askiitians Expert


Sagar Singh


B.Tech, IIT Delhi


















6 years ago
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