Which of the following statements is/are correct about the variation of magnetic declination?
Statement I: Magnetic declination is more at magnetic poles and less at equator.
Statement II: Magnetic declination is more in the summer than in the winter.
Statement III: Magnetic declination is more at night and less in the day.
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A.
Statements I and II only
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B.
Statement I only
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C.
Statement II only
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D.
Statements II and III only
Correct Answer:
B. Statement I only
Explanation:
The correct answer is Statement I only.
Magnetic declination, also known as magnetic variation, is the angle between true north and magnetic north. This value is not constant and varies based on geographic location and time. Statement I is correct because declination generally increases as one moves closer to the magnetic poles, where the horizontal component of the Earth's magnetic field becomes weaker, and decreases near the equator. Statements II and III are incorrect because magnetic declination is primarily influenced by the movement of molten iron in the Earth's outer core (secular variation) rather than by seasonal changes or the time of day. While very minor daily fluctuations exist due to solar activity, they are negligible compared to geographic and long-term variations.
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