Q39.
Consider the following statements: 1. Size of the sun at dusk 2. Colour of the sun at dawn 3. Moon being visible at dawn 4. Twinkle of stars in the sky 5. Polestar being visible in the sky Which of the above are optical illusions?
Answer
C
Explanation
Size of sun at dusk (1) is an optical illusion — when near the horizon, we compare it to known objects and it appears bigger. Colour of sun at dawn (2) is an optical illusion — red light travels farthest, creating the reddish appearance. Twinkle of stars (4) is an optical illusion — due to atmospheric refraction, not actual change in star brightness. Moon visible at dawn (3) is NOT an illusion — it is genuinely visible during half of its lunar cycle. Polestar visible (5) is NOT an illusion.