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The earth's magnetic field varies from p...

The earth's magnetic field varies from point to point in space. Does it also change with time? If so, on what time scale does it change appreciably?

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(a) Over a period of few hundred years, magnetic field of Earth is found to change appreciably. But in the past, it has also been noticed that sometimes it changes on a time scale of few years also.
(Extra Note : In the period of 240 years, between 1580 A.D. to 1820 A.D. magnetic declination of London got changed by `35^(@)` ) .
Moreover, magnetic south pole of Earth is present in the arctic region of Canada. But it is found to be shifting in the north-west direction at a rate of 10 km/year. The reason for changes in the positions of magnetic poles of Earth is still not known).
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KUMAR PRAKASHAN-MAGNETISM AND MATTER-SECTION B Numericals (Numerical From Textual Exercise)
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  2. Answer the question regarding earth's magnetism: Geologists claim t...

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  3. The earth's magnetic field varies from point to point in space. Does i...

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  4. The earth's core is known to contain tron. Yet geologists do not regar...

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  5. The charged currents in the outer conducting regions of the earth's co...

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  6. The earth may have even reversed the direction of its field several um...

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  7. The earth's field departs from its dipole shape substantially at large...

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  8. Interstellar space has an extremely weak magnetic field of the order o...

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  9. A short bar magnet placed with its axis at 30^(@) with a uniform exter...

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  10. A short bar magnet of magnetic moment m=0.32 JT^(-1) is placed in a un...

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  11. A closely wound solenoid of 800 turns and area of cross section 25 xx ...

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  12. If the solenoid in Exercise 5.5 is free to tum about the vertical dire...

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  13. A bar magnet of magnetic moment 1.5 JT^(-1) lies aligned with the dire...

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  14. A closely wound solenoid of 2000 turns and area of cross-section 1.6 x...

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  15. A circular coil of 16 turns and radius 10 cm carrying a current of 0.7...

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  16. A magnetic needle free to rotate in a vertical plane parallel to the m...

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  17. At a certain location in Africa, a compass points 12^@ west of the geo...

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  18. A short bar magnet has a magnetic moment of 0.48 JT^(-1). Give the dir...

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  19. A short bar magnet placed in a horizontal plane has its axis aligned a...

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  20. If the bar magnet in exercise 5.13 is turned around by 180^@, where wi...

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