This document summarizes key concepts related to magnetic effects of electric current. It describes that a current carrying conductor produces a magnetic field around it and experiences a force when placed in an external magnetic field. The direction of the magnetic field and force are determined by Right Hand Rule and Fleming's Left Hand Rule, respectively. Applications discussed include electric motors, which convert electrical to mechanical energy using these principles, and loudspeakers, which use a moving coil in a magnetic field to reproduce sound.

1. MAGNETIC EFFECTS OF
ELECTRIC CURRENT
Shirin Shahana
BSc.Biotechnology

2. MAGNET
• A substance which attracts small pieces of iron and points in North -
South direction when suspended freely in known as Magnet.
• The ones we see are made from them in artificial way.
• Properties of magnet:
• 1) Has 2 poles- North and South.
• 2) Like poles repeal each other and unlike poles attract each other.
• 3) They always exist in pairs of poles.
• 4) Repulsion is the only sure test for a magnet.

3. TYPES OF MAGNET

4. Magnetic field and field lines
1. Magnetic field:-
• The region around a magnet where the force of attraction or
repulsion can be detected is called magnetic field.
• Magnetic field around a magnet can be detected by using a magnetic
compass.

5. 2.Magnetic field lines:-
• Magnetic field lines are the paths around a magnet along which the
north pole of a magnetic compass needle tends to move.
• The magnetic field lines around a magnet can be observed by moving
a magnetic compass kept around a magnet.
i)The magnetic field lines emerge at the north pole and merge at the
south pole.
ii) The magnetic field lines are closer at the poles.
iii) The magnetic field lines do not intersect each other.

6. MAGNETIC FIELD DUE TO A CURRENT
CARRYING CONDUCTOR
• If a magnetic compass is placed near a current carrying conductor
(wire), the needle is deflected.This shows that a conductor carrying
current has a magnetic field around it.
• If the direction of the current is from north to south, the deflection of
the magnetic needle is towards the east.
• If the direction of the current is from south to north, the deflection of
the needle is towards the west.
• The magnetic field around a current carrying straight conductor is in
concentric circles.
• It can be observed by passing a current carrying straight conductor
through a cardboard and sprinkling iron filings on it.

8. RIGHT HAND THUMB RULE
• The direction of the magnetic field around a conductor is given by the
Right Hand Thumb Rule.
• It states that “If a current carrying conductor is held in the right hand
such that the thumb points in the direction of current, then the
fingers wrapped around the conductor shows the direction of the
magnetic field”.

9. MAGNETIC FIELD DUE TO CURRENT IN
CIRCULAR LOOP
• When current is passed through a circular conductor (loop) the
magnetic field produced is in the form of concentric circles around
the conductor.
• Towards the center the arcs of the circles become larger and appear
as straight line.

10. MAGNETIC FIELD DUE TO CURRENT IN
SOLENOID
• A solenoid is an insulated wire wound in the shape of a helix.
• When current flows through a solenoid, it behaves like a bar magnet.
• The ends of the solenoid behaves like the North and South poles of a
magnet.
• The magnetic field produced by a solenoid is similar to the magnetic
field produced by a bar magnet.
• The strength of the magnetic field depends upon the strength of the
current and the number of turns of the coil.

11. • The end of the solenoid at which current flows in the
clockwise direction will be the South Pole and the end
at which current flows in the anticloch vise direction will
be the North Pole.
• The strength of the magnetic field can be increased by:-
1. Increase the number of turns.
2. Increase the strength of current flow.
3. Use soft iron as the core.
4. Increase the area of ​​the cross section of the solenoid.

12. ELECTROMAGNET
• A strong magnetic field inside a solenoid
can be used to magnetize a piece of
magnetic material like a soft iron when
placed inside the coil.
• Such a magnet is called an electromagnet.
• If electric current is passed through a wire
wound around a piece of soft iron, it
behaves like a magnet.
• Such a magnet is called an electromagnet.

14. Force on a current carrying conductor in
Magnetic Field
• A.M.Ampere suggested that,if a current carrying conductor produces
a magnetic field and exerts a force on a magnet, then a magnet
should also exerts a force on a current carrying conductor.
• Eg: - If an aluminum rod is suspended horizontally by a wire between
the poles of a horse shoe magnet and current is passed through the
wire, then the aluminum rod is displaced.
• If the direction of current is reversed, the direction of displacement is
also reversed. The force exerted is maximum if the conductor is
perpendicular to the magnetic field.

16. Flemming’s Left Hand Rule
• The direction of force (motion) of a current carrying conductor in a
magnetic field is given by Fleming's Left Hand Rule.
• It states that,”If we hold the thumb, fore finger and middle finger of
the left hand perpendicular to each other such that the fore finger
points in the direction of magnetic field, the middle finger points in
the direction of current, then the thumb shows the direction of force
(motion) of the conductor.”

18. Eletric Motor

19. • An Electric motor is a device that converts electrical energy to
mechanical energy.
• Working principle:-
“A conductor which can move freely and which is kept in a magnetic
field experiences a force when current passes through it and it moves.”
CONSTUCTION

20. • WORKING
• When current is passed through the coil ABCD, arms AB and CD experience
force.
• According to fleming's left hand rule the force experienced by arm AB is in the
downward direction and arm CD in the upward direction.
• Both these forces are equal and opposite.
• This force rotates the coil in clockwise direction until the coil is vertical.
• At this position, the contact between commutator and brushes break.
• So the supply to the coil is cut off.
• Thus no force acts on the coll. But the coil does not stop due to inertia. It
goes on brushes B1 and B2.
• Again the current starts passing through the coil rotating until the
commutator again comes in contact with the and the arm AB rotates through
900, 1800, 2700 and 360 degrees.
• Now the force acting on arm AB is downward and CD is upward.

22. Moving Coil Loudspeaker
• The electrical pulses from a
microphone are strengthened using an
amplifier and sent through the voice
coil of a loudspeaker.
• The voice coil, which is placed in the
magnetic field, moves to and fro
rapidly, in accordance with the
electrical pulses.
• These movements make the
diaphragm vibrate, thereby
reproducing sound.