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Question
State briefly the molecular theory of magnetism.
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Solution
- Each molecule of a magnetic substance, whether it is magnetized or unmagnetized, is an independent magnet.
- In a magnetized substance, the molecules are arranged in an order so as to produce an external effect. In this order, all the north poles of the molecules of the magnetized substances point to one direction and all their south poles point to a direction opposite to that to which their north poles points.
- In an unmagnetized substance, the molecules are not arranged in any order, so they neutralize the magnetic forces of each other.
- The molecular theory of magnetism was a considerable step forward but later there came an electrical explanation for the magnetism of atoms.
Atoms consist of negatively charged particles (electrons) that revolve around the positively charged nucleus. Electrical current loops are formed in an atom due to the circulation of these electrons. Each current loop behaves a magnetic dipole and hence produce a magnetic field. Also, electrons are also spinning like tops and this adds further magnetism to the atom.
RELATED QUESTIONS
Draw a diagram to show the magnetic field lines around a bar magnet.
The magnetic field lines produced by a bar magnet:
(a) originate from the south pole and end at its north pole
(b) originate from the north pole and end at its east pole
(c) originate from the north pole and end at its south pole
(d) originate from the south pole and end at its west pole
Which of the following statements is incorrect regarding magnetic field lines?
(a) The direction of magnetic field at a point is taken to be the direction in which the north pole a magnetic compass needle points.
(b) Magnetic field lines are closed curves.
(c) If magnetic field lines are parallel and equidistant, they represent zero field strength.
(d) Relative strength of magnetic field is shown by the degree of closeness of the field lines.
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Copy the diagram and label theother poles of the magnets.
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