Q1. [1] medium exam-ready
Assertion (A): When the ciliary muscles of the eye relax, the eye lens becomes thin and its focal length increases.
Reason (R): A thinner lens has less curvature, which decreases its converging power and allows the eye to focus on distant objects.
- A Both A and R are true, and R is the correct explanation of A
- B Both A and R are true, but R is NOT the correct explanation of A
- C A is true but R is false
- D A is false but R is true
Generated by claude-sonnet-4-6 · 2026-06-26 01:07 · grounding rag
Model Answer
Answer: A
Both A and R are true, and R is the correct explanation of A. When ciliary muscles relax, the lens becomes thin (less curvature), reducing converging power, increasing focal length, enabling clear vision of distant objects.
Source: Chapter 10, Section 10.1.1 Power of Accommodation
Explanation
- The textbook directly states: "When the muscles are relaxed, the lens becomes thin. Thus, its focal length increases. This enables us to see distant objects clearly."
- R correctly explains why A happens: a thinner lens → less curvature → less converging power → greater focal length → distant object focus. This is a direct cause-effect chain, so R is the correct explanation of A.
- Choose Option A when both statements are true AND the Reason logically and correctly explains the Assertion.