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Spherical aberration in a lens is due to

Spherical aberration in a lens is due to Correct Answer larger focal length to paraxial rays as compared to marginal rays

CONCEPT:

  • Spherical Aberration: In spherical aberration, rays of light from a point on the optical axis of a spherical lens do not all meet at the same image point.
    • Rays passing closer to the center are focused farther away than the rays passing through a circular zone near its rim.
    • A circular cross-section is formed whenever a plane held perpendicular to the optical axis is made to intersect a cone.
    • The area of the cross-section varies with the distance along the optical axis.
    • The smallest size is known as the circle of least confusion.
    • The most spherical aberration-free image is found at this distance.

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EXPLANATION:

[ alt="371px-Spherical aberration 2.svg" src="//storage.googleapis.com/tb-img/production/21/01/371px-Spherical_aberration_2.svg.png" style="height: 200px; width: 197px;"> 

  • In the above picture, the first  image shows a surface without spherical aberration and the second one with spherical aberration
  • Spherical aberration occurs when paraxial rays have a larger focal length than the marginal rays, both types of rays won't meet at principal focus due to which the image will be blurred
  • Hence, Spherical aberration in a lens is due to the larger focal length of paraxial rays as compared to marginal rays.

Related Questions

Spherical aberration in a lens is due to :
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