Electrodynamics

The Motor Effect
Background

All current carrying conductors are surrounded by a circular magnetic field.
It is amazing to realize that an invisible magnetic field surrounds all the conducting wires around you!
The right-hand wire rule (for conventional currents) is used to determine the direction of this magnetic field.


Hold the wire "naturally" in your right hand, with the current flowing upwards.


This is a diagrammatic view.


Conductor viewed from "above"
Current going perpendicularly INTO PAGE


Conductor viewed from "above"
Current coming perpendicularly OUT OF PAGE

By coiling the wire to form a solenoid (long, cylindrical coil of wire consisting of a number of turns of insulated wire wound close together), the magnetic field is increased.
Inside the solenoid, the magnetic field is uniform.
The strength of the magnetic field is increased hundreds of times if a piece of soft iron is placed inside the solenoid.
This is the principle of the electromagnet.

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