Question

Answer the following question:

A. 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?

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

C. 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?

D. 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 a distant past?

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

F. Interstellar space has an extremely weak magnetic field of the order of ${10^{ - 12}}\,{\text{T}}$ . Can such a weak field be of any significant consequence? Explain.

Answer 1

Hint: Here we have to first see how the earth’s magnetic changes and research deeply about the earth’s core.

The magnetic field of earth also known as the geomagnetic field is the magnetic field which extends into space from the earth’s interior.

Also we have to know about the earth’s magnetic field in detail.

Complete step by step solution:

A. The magnetic field of earth varies over time. It takes a few hundred years for an appreciable sum to change. It is not possible to neglect the variance of the magnetic field of the planet over time.

B. The centre of the earth comprises molten iron. This iron form is not a ferromagnetic one. This is however not known as a type of magnetism on earth.

C. Radioactivity in the centre of the planet is the energy supply that sustains the currents in the outer conducting regions of the centre of the earth. Such charged currents are known as responsible for the magnetism of the planet.

D. During its history of $4$to$5$ billion years, the earth reversed the direction of its field several times. During the solidification, such magnetic fields were weakly documented in rocks, from the analysis of this rock magnetism; one can get clues about geomagnetic history.

E. Owing to the presence of the ionosphere, the earth’s field departs from its dipole structure significantly at broad distances (greater than about $30,000\,{\text{km}}$). In this region, because of the field of single ions, the earth’s magnetic field was modified. These ions generate the magnetic field associated with them whilst in motion.

F. An incredibly weak magnetic field that travels on a circle will bend charged particles. For a wide route distance, this might not be obvious. In relation to giant outer space, the passage of charged particles may be influenced by deflection.

Note: The magnetic field of the earth is created by a self-exciting dynamo mechanism in the liquid outer core. The magnetic field is produced by electrical currents circulating inside the slowly moving molten iron. Variations in earth’s magnetic field often reflect changes in the interior of the earth, while more drastic changes usually occur in the ionosphere or magnetosphere.