Download Magnetic effect of electric current class 10 notes

Magnetic effect of electric current
Magnet: A magnet is an object made of certain materials which create a magnetic field.
There are mainly two types of magnets-permanent magnets and electromagnets.
A permanent magnet A material, or piece of such material, which retains its magnetism even
when not subjected to any external magneticfields.
eg: bar magnet ,horse shoe magnet etc.
Electromagnet: An electromagnet is a type of magnet in which the magnetic field is produced
by an electric current. The magnetic field disappears when the current is turned off.
Uses:
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Transformers
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Motors and generators
 Relays, including reed relays originally used in telephone exchanges
 Electric bells and buzzers
 Loudspeakers and earphones
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Magnetic recording and data storage equipment: tape recorders, VCRs, hard disks
MRI machines
Magnetic locks
Magnetic separation equipment, used for separating magnetic from nonmagnetic material,
for example separating ferrous metal from other material in scrap.
Industrial lifting magnets
Induction heating for cooking, manufacturing, and
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Properties of bar magnet
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magnets have two types of poles: north-seeking poles or north poles and south-seeking
poles or south poles.
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The magnetic strength is the strongest at the poles of the magnet.
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When you freely suspend a bar magnet in a horizontal position, the magnetic field of the
bar magnet will interact with the magnetic field of the Earth. This will cause the bar
magnet to come to rest in a north-south direction, where the north pole of the magnet
points to the north pole of the Earth.
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Like poles repel and unlike poles attract.
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Magnets attract magnetic materials such as iron, steel, cobalt and nickel.
Magnetic materials can be made into magnets
.e.g. Iron, steel, nickel, cobalt and many alloys based on these metals.
magnetic field
The region surrounding a magnet, in which a magnetic force can be experienced is
known as magnetic field.
Magnetic field lines:
A graphical representation of the magnitude and the direction of a magnetic field.
Properties of magnetic field lines
1. The field lines starts from north pole and merge at south pole.
2. Magnetic field lines are closed curves.
3. The field lines are closer ,the field will be stronger.
4. Two field lines never intersect each other. If they did, it would mean that at the point
of intersection ,magnetic field has two direction, which is not possible.
Magnetic effect of electric current
Whenever a current carrying conductor is placed in a magnetic field, a current will be
produced in the conductor. This is known as magnetic effect of electric current. Hans
Christian Oersted discovered this effect first.
Magnetic field due to a current carrying conductor
Concentric circles represent magnetic field of acurrent carrying conductor around a
magnet.These circles become larger and larger as we move away from it because of decrease in
field strength.
Direction of magnetic field around a current carrying conductor is given by Right
hand thumb rule.
Right-Hand thumb rule
Magnetic field due to a current carrying circular loop
The magnetic field around the circular loop would become larger and larger as we
move away from the wire. By the time as we reach at the centre of the circular
loop, arc of these big circles would appear as straight lines.
 The M.F produced by a current carrying conductor at a given point depends
on current passing through it. So a circular coil having n turns, the field
produced is n times as large as that by a single turn. Here the field due to
each turn just adds up.
Solenoid
A coil of many circular turns of insulated copper wire wrapped closely in the
shape of a cylinder is known as a solenoid.
M.F due to a current in a solenoid
The end of the solenoid where current enters acts like a south pole and the other
end where current leaves acts like a north pole. The M.F lines of a solenoid is
similar to a bar magnet. The field is uniform inside the solenoid.
A current carrying solenoid coil is used to magnetize steel or soft iron inside it.
The magnet so formed is an electromagnet.