Advertisements
Advertisements
प्रश्न
State briefly the molecular theory of magnetism.
Advertisements
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
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
A thick wire is hanging form a wooden table. An anticlockwise magnetic field is to be produced around the wire by passing current through this wire by using a battery. Which terminal of the battery should be connected to the:
(a) top end of wire?
(b) bottom end of wire?
Give reason for your choice.
A portable radio has a built-in transformer so that it can work from the mains instead of batteries. Is this a step-up or step-down transformer?
How will you test whether a given rod is made of iron or copper?
[Hint : Iron rod gets magnetised when placed near a bar magnet by magnetic induction, while copper rod does not get magnetised]
Explain what you understand by magnetic induction. What role does it play in attraction of a piece of iron by a magnet?
What conclusion is drawn regarding the magnetic field at a point if a compass needle at that point rests in any direction? Give reason for your answer.
Write a note on the 'magnetic field'.
Select the correct option:
Nickel is a:
Complete the following diagram of magnets to show the lines of force.
Magnetic lines of force never ______ each other.
