♥ Magnetism and Electromagnetism ♥

17.1 The Magnetic Force -- Another Force at a Distance

      A magnetic field is the distribution of a magnetic force in the region of a magnet. The same theory can be applied to magnets as well as electrostatic forces - With electronic fields, there are two different magnetic characteristics, labeled north and south, that are responsible for magnetic forces. 

THE LAW OF MAGNETIC FORCE : Similar magnetic poles, north and north or south and south, repel one another with a force at a distance. Dissimilar poles, north and south, attract one another with a force at a distance. 

    To map a magnetic field you use a test compass, instead of the test charge we used is electrostatics. 
   The Earth itself acts as a giant permanent magnet, producing its own magnetic field. it is suggested that this magnetic field is produced because of the flow of hot liquid metals inside the Earth. Magnets are also known to attract other materials such as iron, nickel, and cobalt, or mixtures of these three. They are called the ferromagnetic metals. 
DOMAIN THEORY: All large magnets are made up of many smaller and rotatable magnets, called dipoles, which can interact with other dipoles close by. if dipoles line up, then a small magnetic domain is produced. 
17.2 Electromagnets
OESTED'S PRINCIPLE : Charge moving through a conductor produces a circular magnetic field around the conductor. 
    To help us predict how magnetic forces act, scientists have developed several hand signs  called right-hand rules because they involve using your right hand. 
↓  Predicts the direction of the magnetic field around a straight conductor. 
RIGHT-HAND RULE #1 for conventional current flow Gasp the conductor with the thumb of the right hand pointing in the direction of conventional, or positive, current low. The curved fingers point in the direction of the magnetic field around the conductor. 
↓  Predicts the relationship between the direction of convectional current flow in a coil and the direction of the magnetic field at the end of the electromagnet. 
RIGHT-HAND RULE #2 for convectional current flow Grasp the coiled conductor with the right hand such that curved fingers point in the direction of conventional, or positive, current flow. The thumb points in the direction of the magnetic field within the coil. Outside the coil, the thumb represents the north end of the electromagnet produced by the coil.