Question

Match the LIST-I with LIST-II 

LIST-I (Aberrations)	LIST-II (Consequences)
A. Spherical aberration	I. image of a point object as a disc
B. Coma	II. spreading of the image along the principal axis
C. Astigmatism	III. Line object is not imaged into a line
D. Distortion	IV. Image of a point object is a blurred surface

Choose the correct answer from the options given below:

• A. A - IV, B - I, C - II, D - III
• B. A - I, B - II, C - III, D - IV
• C. A - IV, B - I, C - III, D - II
• D. A - III, B - IV, C - I, D - II

Hint:

Remember the key features of aberrations:

\textbf{Spherical}: On-axis blur, affects the whole image.
\textbf{Coma}: Off-axis blur, comet-shaped.
\textbf{Astigmatism}: Off-axis blur, point becomes two lines.
\textbf{Distortion}: No blur, shape is wrong (pincushion/barrel).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
This question requires matching different types of monochromatic optical aberrations with their resulting effect on the image.
Step 2: Detailed Explanation:
Let's analyze the best description for each aberration from the given list:


A. Spherical aberration: Occurs when light rays passing through different parts of a spherical lens focus at different points. This causes an on-axis point object to be imaged not as a sharp point, but as a blurred surface. So, A matches IV.
B. Coma: An off-axis aberration that makes an off-axis point object appear as a comet-shaped blur. A simplified description of this blur, particularly its head, is an image of a point object as a disc. So, B matches I.
C. Astigmatism: An off-axis aberration where rays in different planes (e.g., vertical and horizontal) focus at different distances from the lens. This causes the focal points to be spread out along the optical axis, with two distinct line foci. This can be described as the spreading of the image along the principal axis. So, C matches II.
D. Distortion: Occurs when the magnification of the lens varies with distance from the optical axis. This does not blur the image but deforms its shape. For example, a straight line in the object that does not pass through the center will be imaged as a curved line. Thus, a Line object is not imaged into a (straight) line. So, D matches III.

Step 3: Final Answer:
Based on the most plausible interpretation of the descriptions, the correct matching is A-IV, B-I, C-II, D-III.