Magnetic poles exist in pairs, called the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole and the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole.

Like poles attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth, unlike poles attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth.

A Magnetic Field is any attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth of space where magnetic forces can be attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth.
You must also remember that Magnetic Field Lines always go from the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole to the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole.




Determining the direction of a Magnetic Field due to an Electric Current.

For a straight wire use the right hand grip rule:

Grip the conductor in your attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth hand, with your thumb pointing in the direction of the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth; your fingers now indicate the attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth of the magnetic field attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth.

For a solenoid:

The direction of the magnetic field in a solenoid is to note that when looking into a loop or solenoid, if the current is moving in a Clockwise direction then the current facing you is a attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole ; anti-clockwise represents a attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth Pole.



To Demonstrate the Magnetic Effect of an Electric Current:
The Electromagnet

An electromagnet consists of a soft attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth core in a attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth. When the current is switched on the core acts as a attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth and can be used to pick up nails.

(A solenoid is a coil of wire whose length is much longer than its radius).

Uses of Electromagnets
• Electromagnets can be used in attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth yards to lift cars.
• They are also used in electric attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth, loudspeakers and electromagnetic relays (eg in doorbells).




The Earth’s Magnetic Field

The Earth’s magnetic field can be used for accurate attractcurrentdirectionfeltironlinesmagnetmotorsnavigationNorthregionrepelrightscrapsolenoidSouth.