Electric motor power point presentation

Electric motor power point presentation

1. Electric MotorElectric Motor
By Princess BarcegaBy Princess Barcega
APG SchoolAPG School
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2. Magnetic Force On A Current – Magnetic Force On A Current –
Carrying Conductor Carrying Conductor
The magnetic force (F) the conductor The magnetic force (F) the conductor
experiences is equal to the product of its experiences is equal to the product of its
length (L) within the field, the current I in length (L) within the field, the current I in
the conductor, the external magnetic field the conductor, the external magnetic field
B and the sine of the angle between the B and the sine of the angle between the
conductor and the magnetic field. In shortconductor and the magnetic field. In short
F= BIL (sinF= BIL (sin))

3. The force on a currentThe force on a current--carrying carrying
conductor in a magnetic fieldconductor in a magnetic field: :
When a currentWhen a current--carrying conductor is placed in a magnetic carrying conductor is placed in a magnetic
field, there is an interaction between the magnetic field field, there is an interaction between the magnetic field
produced by the current and the permanent field, which produced by the current and the permanent field, which
leads to a leads to a forceforce being experienced by the conductor: being experienced by the conductor:

4. The magnitude of the force on the conductor depends The magnitude of the force on the conductor depends
on the magnitude of the current which it carrieson the magnitude of the current which it carries. . The The
force is a maximum when the current flows force is a maximum when the current flows
perpendicularperpendicular to the field (as shown in diagram A on to the field (as shown in diagram A on
the left below), and it is zero when it flows the left below), and it is zero when it flows parallelparallel to to
the field (as in diagram B, on the right):the field (as in diagram B, on the right):

5. Fleming’s left-hand ruleFleming’s left-hand rule

6. The directional relationship The directional relationship
of I in the conductor, the of I in the conductor, the
external magnetic field and external magnetic field and
the force the conductor the force the conductor
experiencesexperiences
I
F
B

7. Motion of a current-carrying loop in a Motion of a current-carrying loop in a
magnetic fieldmagnetic field
N
S
LR
I
F
F
Rotation
Commutator
(rotates with
coil)
brushes

8. Vertical position of the loopVertical position of the loop::
N
S
Rotation

9. Electric MotorElectric Motor
An electromagnet is the basis of an An electromagnet is the basis of an
electric motor electric motor
An electric motor is all about magnets and An electric motor is all about magnets and
magnetismmagnetism: : A motor uses A motor uses magnetsmagnets to to
create motion. create motion.
Opposites attract and likes repelOpposites attract and likes repel. . Inside an Inside an
electric motor, these attracting and electric motor, these attracting and
repelling forces create repelling forces create rotational motionrotational motion. .
A motor is consist of two magnets.A motor is consist of two magnets.

10. Parts of the MotorParts of the Motor
Armature or rotor Armature or rotor
Commutator Commutator
Brushes Brushes
Axle Axle
Field magnet Field magnet
DC power supply of some sortDC power supply of some sort

11. Motor IllustrationMotor Illustration

12. ArmatureArmature
The armature is an The armature is an
electromagnet made by electromagnet made by
coiling thin wire around coiling thin wire around
two or more poles of a two or more poles of a
metal core.metal core.
The armature has an The armature has an axleaxle, ,
and the commutator is and the commutator is
attached to the axle. attached to the axle.
When you run electricity into When you run electricity into
this electromagnet, it creates this electromagnet, it creates
a magnetic field in the a magnetic field in the
armature that attracts and armature that attracts and
repels the magnets in the repels the magnets in the
statorstator. . So the armature spins So the armature spins
through 180 degreesthrough 180 degrees..
To keep it spinning, you have To keep it spinning, you have
to change the poles of the to change the poles of the
electromagnet.electromagnet.

13. Commutator and BrushesCommutator and Brushes
Commutator is simply a pair of plates Commutator is simply a pair of plates
attached to the axleattached to the axle. . These plates provide These plates provide
the two connections for the coil of the the two connections for the coil of the
electromagnetelectromagnet. .
Commutator and brushes work together to Commutator and brushes work together to
let current flow to the electromagnet, and let current flow to the electromagnet, and
also to flip the direction that the electrons also to flip the direction that the electrons
are flowing at just the right momentare flowing at just the right moment. .

14. The contacts of the commutator are attached to The contacts of the commutator are attached to
the axle of the electromagnet, so they spin with the axle of the electromagnet, so they spin with
the magnetthe magnet. . The brushes are just two pieces of The brushes are just two pieces of
springy metal or carbon that make contact with springy metal or carbon that make contact with
the contacts of the commutatorthe contacts of the commutator..

15. Spinning ArmatureSpinning Armature

16. Example of MotorExample of Motor

17. Answer the questionsAnswer the questions

18. A current-carrying coil in a magnetic field
experiences a turning effect.
How can the turning effect be increased?
A increase the number of turns on the coil
B reduce the size of the current
C reverse the direction of the magnetic field
D use thinner wire for the coil

19. What are the directions of the force in the left What are the directions of the force in the left
and right loop?and right loop?

20. A student sets up the apparatus shown in
order to make a relay.
Which metal should be used to make the core?
A aluminium B copper
C iron D steel