EARTH SCIENCE
MAGNETISM
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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True
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False
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Either A or B
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None of the above
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Detailed explanation-1: -It has always been a feature of our planet, but it has flipped in polarity repeatedly throughout Earth’s history. Each time it flips – up to 100 times in the past 20 million years, while the reversal can take about 1, 000 years to complete – it leaves fossilised magnetisation in rocks on Earth.
Detailed explanation-2: -Magnetic Pole Reversals While that may sound like a big deal, pole reversals are common in Earth’s geologic history. Paleomagnetic records tell us Earth’s magnetic poles have reversed 183 times in the last 83 million years, and at least several hundred times in the past 160 million years.
Detailed explanation-3: -But the magnetic poles can, and do, undergo complete reversals, most recently around 780, 000 years ago. The weakening of the magnetic field as it undergoes a complete flip would make the Earth more vulnerable to the effects of solar radiation, which have the power to disrupt powerlines and telecommunications.
Detailed explanation-4: -According to the latest IGRF, the Pole is currently moving in the same direction but at a slightly reduced speed of about 45 km per year. NCEI and CIRES scientists created an animation showing changes in declination location and the “wandering” of the North Magnetic Pole over the last 50 years.
Detailed explanation-5: -A team of researchers used volcanic records to study Earth’s last magnetic-field reversal, which occurred about 780, 000 years ago. They found that this flip may have taken much longer than researchers previously thought, the scientists reported in a new study.