Q2 of 44 Page 200

Answer the following questions:

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

Earth changed its magnetic orientation several times in history. The magnetic orientation of the earth were weekly recorded in the rocks during solidification.


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2

Answer the following questions:

The earth’s core is known to contain iron. Yet geologists do not regard this as a source of the earth’s magnetism. Why?

 2

Answer the following questions:

The charged currents in the outer conducting regions of the earth’s core are thought to be responsible for earth’s magnetism. What might be the ‘battery’ (i.e., the source of energy) to sustain these currents?

 2

Answer the following questions:

The earth’s field departs from its dipole shape substantially at large distances (greater than about 30,000 km). What agencies may be responsible for this distortion?

 2

Answer the following questions:

Interstellar space has an extremely weak magnetic field of the order of 10–12 T. Can such a weak field be of any significant consequence? Explain.