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The earth may have even reversed the dir...

The earth may have even reversed the direction of its field several umes during its bustory of 4 to 5 billion years. How can geologists know about the earth's field in such distant past?

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(d) Magnetic poles of Earth are found to be changing their positions at a rate of 10 km/ year. Study made so far in this regard has shown that positions of magnetic field of Earth get reversed over `10^6` years approximately.
At the bottom of sea, basalt comes out from volcano explosions which contains iron. This gives indication of above phenomenon. When this basalt cools down and becomes solid, it gives information of magnetic field of Earth. Life of such solid rocks can be estimated which ultimately indicates reversal of magnetic field of Earth.
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KUMAR PRAKASHAN-MAGNETISM AND MATTER-SECTION B Numericals (Numerical From Textual Exercise)
  1. Answer the question regarding earth's magnetism: Geologists claim t...

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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  20. A short bar magnet of magnetic moment 5.25 xx 10^(-2) JT^(-1) is place...

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