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ICSE Class 9 Answered

1. What is the releation of current with magnetism ? 2. How can magnets attract magnetic substances ? 3. Why can magnet only attract only magnetic particles ?
Asked by Sujitkumarm | 18 Dec, 2021, 09:56: PM
Expert Answer
Magnetism is due to current flow of flow of charge carriers . As shown in figure ,
when a current is flowing through a conducting wire,we get magnetic field around the current carrying wire.
Intensity of magnetic field at a point is proportional to the current passing through wire and
inversely proportional to the nearest distance from wire.

If current is passed through a loop made of conducting wire , this current carrying loop is considered as magnetic dipole .
Magnetic dipole moment μ is defined as μ = i A  , where i is the current passing through loop and A is area of loop
Spinning and orbital motion of electron in the magnetic substances act as tiny magnetic dipole .
( magnetic monopole does not exist)
These tiny dipoles are randomly oriented in different directions and give net magnetic field  zero in absence of external magnetic field.
When external magnetic field is present , then this magnetic field aligns the tiny dipoles of magnetic substance in the direction of external magnetic field.
Hence magnetic substance become magnet.
In this way magnetic field due to magnet makes the magnetic substance another magnet , hence magnetic substances are attracted by magnets.
tiny magnetic dipoles due to elctron spinning and orbital motion is present only in magnetic materials .
Iin non-magnetic materials these tiny dipole moments are cancelled due to atomic structure of magnetic substances.
Hence only magnetic materials are getting magnetised due to magnetic field of magnet and is getting attracted by magnet.

Answered by Thiyagarajan K | 19 Dec, 2021, 09:09: AM

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