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प्रश्न
State briefly the molecular theory of magnetism.
उत्तर
- 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.
संबंधित प्रश्न
Define magnetic field lines. Describe an activity to draw a magnetic field line outside a bar magnet from one pole to another pole.
The magnetic field inside a long straight solenoid carrying current ______.
Explain the following :
Several soft iron pins can cling, one below the other, from the pole of a magnet.
Explain the following :
The north end of a freely suspended magnetic needle gets attracted towards a piece of soft iron placed a little distance away from the needle.
In following figure, draw at least two magnetic field lines between the two magnets.
(b) 
Draw the pattern of magnetic field lines near a bar magnet placed with its North Pole pointing towards the geographic North. Indicate the position of neutral points by marking X.
Draw diagram showing the arrangement of the lines of force for a piece of soft iron laid in line with the magnetic field.
Distinguish between
Magnetic properties of iron and steel.
Inside the magnet, the field lines moves ____________.
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.
