DC Current Electricity and Magnetism in Electrical Conductors

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

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

Electric Fields Drive Current Electricity

Conventional CurrentAssumes Charge Flows from Positive to NegativeCationAnion

Ions contain CHARGES that create electric fieldsCurrent ElectricityBatteries use electrochemical reactions to produce dissimilar charges used to create current in DC motors and circuits.

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

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

When current moves through a conductor a circular magnetic field is induced around the conductorMagnetic Field LinesDirection of Conventional CurrentNegative Battery TerminalPositive Battery Terminal

The Right Hand RuleThe direction of the magnetic field surrounding the conductor can be found using your right handPosition 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.

The Direction and Motion of an Induced Magnetic Field in a ConductorCurrent Coming Towards YouCurrent Moving Away From You

When current moves through a coiled conductor a circular magnetic field is induced about the coilCurrent and Magnetism in a Coil

Motor (armature) rotation is caused by the simultaneous attraction and repulsion between the electromagnetic field in the armature and a fixed magnetic fieldArmature

A Conductor in a Fixed Magnetic FieldA Current Carrying Conductor in a Fixed Magnetic Field

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

Fleming's Left Hand (Motor) RuleDetermines the direction of DC current carrying conductor in a fixed magnetic fieldThumb = Direction of Conductor MotionFore Finger = Direction of Fixed Magnetic Field (N to S)Middle Finger = Conventional Current Direction

Fleming's Left Hand (Motor) RuleNSDirection of RotationFixed Magnetic Field DirectionConventional Current Direction

NSUse the Left Hand Rule to Determine the Rotation Direction of the Armatures in A and BNotice that when the current through the armature is reversed, it moves (Rotates) in the opposite directionABHint: You will have to turn your left hand upside down for example A

Two parallel conductors carrying current in the same direction will attract each otherMagnetic Forces Acting on Parallel Current Carrying Conductors

Magnetic Forces Acting on Parallel Current Carrying ConductorsXTwo parallel conductors carrying currents in opposite directions will repel each other, and they will set up a polarized magnetic field between themselves.NorthSouth

Magnetic Forces Acting on Parallel Current Carrying ConductorsSouthNorthSouthNorthWrapping current carrying conductors around an iron core creates an electro magnet

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

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