Assertion (A): The apparent position of a star near the horizon is slightly higher than its actual position.
Reason (R): The earth's atmosphere refracts starlight, bending it towards the normal as it passes through layers of increasing density.
Generated by claude-sonnet-4-6 · 2026-06-26 01:07 · grounding rag
Model Answer
Option A — Both A and R are true, and R is the correct explanation of A.
Atmospheric refraction bends starlight towards the normal as it travels through increasingly dense layers, making the star appear slightly higher than its actual position near the horizon.
Source: Chapter 10, Section 10.5 – Atmospheric Refraction
Explanation
- A is true: The textbook explicitly states "The star appears slightly higher (above) than its actual position when viewed near the horizon."
- R is true: The atmosphere bends starlight towards the normal as density increases — this is standard refraction behaviour.
- R correctly explains A: The upward apparent shift is a direct result of this refraction — so R is the correct explanation, making Option A the right choice.
- Key phrase to remember: "Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position."