2013
Q. 14
Set A
Geography
Physical Geography
Variations in the length of daytime and nighttime from season to season are due to
Smart Elimination
When two statements describe the Earth’s revolution in different ways, UPSC is likely considering one of them correct — so don’t eliminate both revolution-related statements.
Potential Trap
Confusing Rotation (Day/Night existence) with Revolution/Tilt (Variation in length).
Answer Key & Explanation
Answer: DThe correct answer is Option D.
Explanation:
- Rotation on Axis: Causes the occurrence of Day and Night.
- Revolution + Tilt: The variation in the length of day and night from season to season is due to the revolution of the earth around the sun combined with the inclination (tilt) of the earth's axis (23.5 degrees).
- If the axis were not tilted, days and nights would be equal (12 hours) everywhere throughout the year.
Value Addition
- Solstice: Summer Solstice (longest day in hemisphere), Winter Solstice (shortest day).
- Equinox: Equal day and night (Sun overhead at Equator).
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Questions
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Difficulty Assessment
easy
Foundational question based on core concepts.