Q2 of 44 Page 200

Answer the following question:

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?

The earth’s magnetic field changes with time due to many reasons, changes is the speed of convection current in core is one of them. These changes are very slow and will take hundreds of years to show substantial effects.


More from this chapter

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1

Answer the following question regarding earth’s magnetism:

The earth’s field, it is claimed, roughly approximates the field due to a dipole of magnetic moment 8 × 1022 J T–1 located at its centre. Check the order of magnitude of this number in some way.

 1

Answer the following question regarding earth’s magnetism:

Geologists claim that besides the main magnetic N-S poles, there are several local poles on the earth’s surface oriented in different directions. How is such a thing possible at all?

 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?