# Magnetism and Matter

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Do you know that the earth’s magnetic field varies from point to point in space? Do you know what is the reason behind this? Many folks also want to understand about the region and its weak magnetic flux .

We will determine the magnitude of the moment of a magnet of a magnet with a particular degree of the uniform magnetic flux and what is going to happen if the magnet is rotated freely during a plane and what is going to be the P.E. of the magnet. Do you know once we pass through the solenoid, it acts sort of like a magnet, finding out what's the moment of a magnet of this solenoid?

We will be seeing here, what proportion torque is required for turning a magnet in order that its moment of a magnet is at a particular alignment with the sector . We will be seeing an example of a magnet wont to determine meridian points and computing the direction and magnitude of the earth’s magnetic flux . There are various examples, exemplary questions, MCQ’S and worksheets mentioned below which can assist you understand magnetism and therefore the magnetic flux with its uses and application. Practising the problems on magnetism will definitely help you in the retention of these concepts as the topics are frequently asked in examinations.

Distant galaxies, humans and beasts, tiny invisible atoms are all penetrated by magnetic fields from a spread of sources over and once again . Hence, we will say that magnetic phenomena are universal in nature. In the previous chapter, we studied the connection between electricity and magnetism. In this chapter, we take a look at magnetism in its own right. One learns the following topics in this chapter:

Description of a magnet and its behaviour in an external magnetic flux

Gauss’s law of magnetism followed up with an account of the earth’s magnetic flux

Classification of materials based on their magnetic properties

Electromagnets and permanent magnets

Important Question Related to Magnetism and Matter

(a) The earth’s magnetic flux varies from point to point in space. Does it also change with time? If so, on what duration does it change appreciably?

(b) The earth’s core is understood to contain iron. Yet geologists don't regard this as a source of the earth’s magnetism. Why?

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

(d) the world may have even reversed the direction of its field several times during its history of 4 to five billion years. How can geologists realize the earth’s field in such a distant past?

(e ) region has a particularly weak magnetic flux of the order of 10–12 T.Answer 5.2:

(a) Earth’s magnetic field varies with time and it takes a couple of hundred years to change by an obvious sum. The variation in the Earth’s magnetic field with respect to time can’t be ignored.

(b) The Iron core at the Earth’s centre can't be considered as a source of Earth’s magnetism because it's in its molten form and is non-ferromagnetic.

(c) The radioactivity in earth’s interior is the source of energy that sustains the currents within the outer conducting regions of earth’s core.

(d) The Earth’s magnetic field reversal has been recorded several times in the past about 4 to 5 billion years ago.

(e) Due to the presence of ionosphere, the Earth’s field deviates from its dipole shape substantially at large distances. The Earth's field is slightly modified in this region because of the field of single ions. The magnetic flux related to them is produced while in motion.

(f) A remarkably weak magnetic field can deflect charged particles moving in a circle. This may not be detectable for an outsized radius path. With regard to the large region , the deflection can alter the passage of charged particles.

(a) The three independent conventional quantities used for determining the earth’s magnetic flux are:

(i) Magnetic declination,

(ii) Angle of dip

(iii) Horizontal component of earth’s magnetic field

(b) The angle of dip at some extent depends on how far the purpose is found with reference to the North Pole or the South Pole . Hence, as the location of Britain on the globe is closer to the magnetic North pole, the angle of dip would be greater in Britain (About 70°) than in southern India.

(c) it's assumed that an enormous magnet is submerged inside the world with its North Pole near the geographic South Pole and its South Pole near the geographic North Pole.

Magnetic field lines originate from the north pole and terminate at the magnetic South Pole . Hence, during a map depicting earth’s magnetic flux lines, the sector lines at Melbourne, Australia would appear to maneuver faraway from the bottom.

(d) If a compass is placed in the geomagnetic North Pole or the South Pole, then the compass will be free to move in the horizontal plane while the earth’s field is exactly vertical to the magnetic poles.