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प्रश्न
State briefly the modern views on magnetism.
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उत्तर
The molecular theory of magnetism was a considerable step forward but later there came an electrical explanation for the magnetism of atoms and this had wider applications. We have already seen that magnets can be made by an electric current. Atoms contain particles of electricity called electrons that move in orbits about a central nucleus. These electrons behave like an electric current in a single turn of wire and so create a magnetic field. More importantly, the electrons are also spinning like tops and this adds further magnetism to the atom.
The apparently non-magnetic substances are classified as either diamagnetic or paramagnetic respectively. We shall explain these terms very briefly before going on to deal with the strongly magnetic or ferromagnetic substances.
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संबंधित प्रश्न
Draw a diagram to show the magnetic field lines around a bar magnet.
The shape of the earth's magnetic field resembles that of an imaginary:
(a) U-shaped magnet
(b) Straight conductor carrying current
(c) Current-carrying circular coil
(d) Bar magnet
Copy the figure below which shows a plotting compass and a magnet. Label the N pole of the magnet and draw field line on which the compass lines
Figure. shows a bar magnet placed on the table top with its north pole pointing towards south. The arrow shows the north-south direction. There are no other magnets or magnetic materials nearby.
Indicate by crosses, the likely positions of the neutral points.
What do you meant by the term pole of a magnet? Magnetically speaking, what is the difference between a piece of brass, a piece of soft iron, and a piece of lode- stone?
Define the Isogonic line.
Repulsion is a surer test of magnetic condition of a body than attraction. Explain.
Complete the following diagram of magnets to show the lines of force.
A closely wounded circular coil of radius 5 cm produces a magnetic field of 37.68 × 10-4 T at its center. The current through the coil is ______ A. [Given, number of turns in the coil is 100 and π = 3.14)
Assertion (A): Magnetic field lines never intersect each other.
Reason (R): If they intersect, then at the point of intersection, the compass needle would point towards two directions, which is not possible.
