DC Current Electricity and Magnetism in Electrical Conductors

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.

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 Current Assumes Charge Flows from Positive to Negative CationAnion

Ions contain CHARGES that create electric fields Current Electricity Batteries 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 Electricity The 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 conductor Magnetic Field Lines Direction of Conventional Current Negative Battery Terminal Positive Battery Terminal

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.

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

When current moves through a coiled conductor a circular magnetic field is induced about the coil Current 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 field Fixed Magnets Armature

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

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)

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

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

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

Two parallel conductors carrying current in the same direction will attract each other 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

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

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

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