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1. Magnetic Effects
Magnetic Effects
Of
Of
Electric
Electric
Current
Current
in one shot

2. Introduction
Magnetic Field and Field Lines
Magnetic field due to Current-
Carrying conductor
Force on a Current - Carrying
Conductor in a Magnetic Field
AC and DC
Domestic Electric Current
Topics to be Discussed

3. Properties of Magnet :-
• A free suspended magnet always points towards the
north and south direction.
• The pole of a magnet which points toward north
direction is called north seeking or north pole.
• The pole of a magnet which points toward south
direction is called south seeking or south pole.
• Like poles of magnets repel each other while unlike
poles of magnets attract each other.
Magnet is any substance that attracts iron / iron–like substances.

4. Magnetic Field and Field Lines
Direction
Magnitude
The area around a magnet where a magnetic force is
experienced is called the magnetic field.
Magnetic field is a quantity that has both
The magnetic field lines can be
explained as imaginary lines that graphically
represent the magnetic field acting around
a magnet.

5. Outside the magnet, the direction of magnetic field line is taken
from North pole to South Pole. Inside the magnet, the direction
of magnetic field line is taken from South pole to North pole.
• They are continuous and form closed curves.
• Magnetic field lines never intersect each other.
• If field lines are close, field is stronger.
If field lines are far apart, field is weak .
Properties of Magnetic Field Lines

6. Hans Christian Oersted discovered that when electric current flows through
a current carrying conductor, it produces a magnetic field around it. This can
be seen with the help of a magnetic needle which shows deflection.
The more the current, the higher the deflection.
If the direction of current is reversed, the
direction of deflection is also reversed.
Through this observation Oersted showed that
electricity and magnetism were related phenomena.
Oersted’s experiment :-

7. A current carrying straight conductor has magnetic field in the
form of concentric circles, around it.
The direction of magnetic field through a current carrying
conductor depends upon the direction of flow electric current.
The Magnetic field produced is directly proportional to the current
& inversely proportional to the distance from the conductor.
Magnetic Field due to a Straight
Current - Carrying Conductor

9. It states that, if you hold the current carrying straight wire
in the grip of your right hand in such a way that stretched thumb points
in direction of current, then the direction of the curl of the fingers will
give the direction of magnetic field.
Maxwell's Right Hand Thumb Rule

10. Magnetic Field due to a Current through a Circular Loop
Every point on the circular loop will
act as a straight conductor.
Magnetic field lines are closer near the
conductor which means the magnetic
field is stronger near the periphery of
the loop.
Magnetic field lines move away from
each other as we move towards the
centre of the current carrying loop.
At the centre, the magnetic field lines
appear as straight lines

11. Magnetic Field ∝Current passing through the conductor
Magnetic Field ∝ 1
Magnetic Field ∝No. of turns in the coil
Factors affecting Magnetic Field of a Circular Current
Carrying Conductor
Distance from the conductor

12. Magnetic field is additive in nature i.e., magnetic field of one loop adds up to magnetic
field of another loop. This is because the current in each circular turn has some direction.

13. Magnetic Field due to a Current in a Solenoid
Solenoid is the coil with many circular
turns of insulated copper wire wrapped
closely in the shape of a cylinder.
A current carrying solenoid produces
similar pattern of magnetic field as a bar
magnet. One end of solenoid behaves as
the north pole and another end behaves
as the south pole.
Magnetic field lines are parallel inside
the solenoid, similar to a bar magnet,
which shows that magnetic field is same
at all points inside the solenoid.

14. A temporary magnet of soft iron core
with a coil wound around it which
retains magnetism only when current
passes through the coil.
It is used in electric bells, telephones,
electric motor etc.
Electromagnet

15. Fleming’s Left-Hand Rule
Fleming’s Left Hand Rule states that
if we arrange our thumb, forefinger
and middle finger of the left-hand
perpendicular to each other, then
the thumb points towards the
direction of the force experienced
by the conductor, the forefinger
points towards the direction of the
magnetic field and the middle finger
points towards the direction of the
electric current.

16. AC and DC Current

17. There are three kinds of wires used:
(i) Live wire (positive) with red insulation cover
(ii) Neutral wire (negative) with black insulation cover
(iii) Earth wire with green insulation cover.
Domestic Electric Circuits
→ The potential difference between live and neutral wire in India is 220 V.

18. Pole ⇒Main supply ⇒Fuse ⇒Electricity meter ⇒Distribution box ⇒To separate circuits
• Short Circuit: A sudden flow of a very large current due to direct contact of a live wire and a
neutral wire is called short-circuiting. The resistance of the circuit becomes almost zero.
• Overloading: When current drawn is more than current carrying capacity of a conductor, it
results in overloading. Electric fuse melts when a large current flow through the circuit.