2. Electromagnetism manifest as both electric fields and magnetic fields. Both fields are simply different aspects of electromagnetism, and hence are intrinsically related. Thus, a changing electric field generates a magnetic field; conversely a changing magnetic field generates an electric field.

Electric and magnetic forces can be detected in regions called electric and magnetic fields. These fields are fundamental in nature and can exist in space far from the charge or current that generated them. Remarkably, electric fields can produce magnetic fields and vice-versa, independent of any external charge. A changing magnetic field produces an electric field, as the English physicist Michael Faraday discovered in work that forms the basis of electric power generation. Conversely, a changing electric field produces a magnetic field, as the Scottish physicist James Clerk Maxwell deduced. The mathematical equations formulated by Maxwell incorporated light and wave phenomena into electromagnetism. He showed that electric and magnetic fields travel together through space as waves of electromagnetic radiation, with the changing fields mutually sustaining each other.

recursion process :
1} electric charges attract or repel one another with force inversely proportional to the square of the distance between them: unlike charges attract, like ones repel.

2} magnetic poles (or states of polarization at individual points) attract or repel one another in a similar way and always come in pairs: every north pole is yoked to a south pole.

3} an electric current in a wire creates a circular magnetic field around the wire, its direction (clockwise or counter-clockwise) depending on that of the current.

4} a current in induced in a loop of wire when it is moved towards or away from a magnetic field, or a magnet is moved towards or away from it, the direction of current depending on that of the movement.

design team: Mengyi Fan & Lefevre Marguerite
ENCODED MATTER, GSAPP 2011
Instructor: Ezio Blasetti

OPTEK Technology OH090U - Simple Hall Effect Sensor Switch
Melexis US1881 - Latching Hall Effect Sensor
Allegro A1321 - Ratiometric Linear Hall Effect Sensor

See all my arduino articles: adam-meyer.com/arduino/