DC current electricity and magnetism in electrical conductors are described. An electric field radiates from a positive charge and toward a negative charge. Current is measured by the amount of charge passing through a conductor over time. Batteries use electrochemical reactions to produce dissimilar charges that create current. This current produces a circular magnetic field around the conductor according to the right hand rule. A motor's armature rotation is caused by attraction and repulsion between its electromagnetic field and a fixed magnetic field. Fleming's left hand rule determines the direction of a DC current-carrying conductor in a fixed magnetic field. Parallel conductors carrying current in the same direction attract, while those with opposite current repel. Wrapping conductors around an

1. DC Current Electricity
and
Magnetism
in
Electrical Conductors

2. Electric Field
An Electric Field or Force Surrounding a Charged Particle
An electric field radiates outward from a positive charge and
radiates in toward a negative point charge.

3. •The movement of Electric Charges is called Current.
• Current is measured by the amount of charge
(Coulombs) passing through the cross-sectional area of
a conductor in a given period of time (Seconds).
•A Conventional Current flows from a positive battery
terminal to a negative battery terminal.
Current Electricity

4. Electric Fields Drive Current Electricity

5. Conventional Current
Assumes Charge Flows from Positive to Negative
CationAnion

6. Ions contain CHARGES that create
electric fields
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Current Electricity
Batteries use
electrochemical
reactions to
produce
dissimilar
charges used to
create current
in DC motors
and circuits.

7. Ions contain CHARGES that create electric fields. These
opposite electric fields produce imbalanced forces necessary
to move the charges through the circuit.
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Current Electricity
The electric
field produced
in a battery
forces current
through an
electric circuit
or conductor
connected
across the
battery poles,

8. A current created by the unidirectional movement of
charge(s) through a conductor is called a direct current.
This current is produced by all batteries
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9. When current moves through a conductor a circular
magnetic field is induced around the conductor
Magnetic Field Lines
Negative Battery
TerminalPositive Battery
Terminal

10. The Right Hand Rule
The direction of the magnetic field
surrounding the conductor can
be found using your
right hand
Position the thumb of your right hand
pointing in the direction of
conventional current (Positive to
Negative) and your fingers will wrap
around the conductor in the direction
of the induced magnetic field.

11. The Direction and Motion of an Induced
Magnetic Field in a Conductor
Current Coming
Towards You
Current Moving
Away From You
X

12. When current moves through a coiled conductor a
circular magnetic field is induced about the coil
Current and Magnetism in a Coil

13. Motor (armature) rotation is caused by the simultaneous
attraction and repulsion between the electromagnetic
field in the armature and a fixed magnetic field
Fixed Magnets
Armature

14. Induced Magnetic Field
(Due to current)
Fixed Magnetic Field
Force
A Conductor in a Fixed
Magnetic Field
A Current Carrying Conductor
in a Fixed Magnetic Field

15. N
S
A Motor Armature in a Fixed
Magnetic Field
The magnetic field surrounding a current
carrying conductor interacts with an
existing magnetic field.
Direction of Force (Torque) acting
to turn the Armature (Conductor)

16. Fleming's Left Hand (Motor) Rule
Determines the direction of DC current
carrying conductor in a fixed magnetic field
Thumb = Direction of
Conductor Motion Fore Finger = Direction of
Fixed Magnetic Field (N to S)
Middle Finger =
Conventional
Current Direction

17. Fleming's Left Hand (Motor) Rule
N
S
Direction of Rotation
Fixed Magnetic Field Direction
Conventional
Current Direction

18. N
S
N
S Use the Left Hand Rule to
Determine the Rotation
Direction of the Armatures
in A and B
Notice that when the
current through the
armature is
reversed, it moves
(Rotates) in the
opposite direction
A
B
Hint: You will have to turn
your left hand upside down
for example A

19. Two parallel conductors carrying current
in the same direction will attract each
other
Magnetic Forces Acting on Parallel
Current Carrying Conductors

20. Magnetic Forces Acting on Parallel
Current Carrying Conductors
X
Two parallel
conductors
carrying currents
in opposite
directions will
repel each
other, and they
will set up a
polarized
magnetic field
between
themselves.
North
South

21. Magnetic Forces Acting on Parallel
Current Carrying Conductors
X
South
North
South
North
Wrapping current carrying conductors around
an iron core creates an electro magnet

22. The Armature of a Brush Commutated DC
Motor is made up of Current Carrying
Conductors Wrapped Around an Iron Core
The Motor Armature is an electro Magnet and
Operates according to the Principles Described in
this Slide Show

23. The End