AC vs. DC Current Electromagnetic Fields

DC  Direct Current Current that is produced in a circuit by a steady voltage source. Direct current is when electrons flow in one direction in a circuit only. In direct current the voltage will go to maximum or PEAK (almost) instantly so on a graph it looks like this.  Electrons flow from – to + Volts Time 1 sec

AC  Alternating Current Current that is produced by a voltage source that changes polarity, or alternates, with time. In alternating current the voltage goes to PEAK positively then reverses to zero, the current then goes to PEAK in the negative. When the electrons have gone once in each direction makes cycle and is represented with a sine wave as seen in the graph. When armature cuts magnet field at peak When armature runs parallel to field at zero http://www.walter-fendt.de/ph14e/generator_e.htm Link needs Java to run Volts Time Link to http://www.walter-fendt.de/ph14e/generator_e.htm under the title AC Alternating Current Draw this graph on your paper

Electromagnetic Fields When current flows through a conductor a magnetic field is produced about the conductor. The magnetic field does not have a north or south pole but it does have direction which is determined by the direction of the current. A compass will deflect when in the area of these electrically induced magnetic field

Wire in a coil Take the same wire as in the previous slide and put the wire into a coil and now the magnetic field will have a north and south pole. Add an iron core and this increases the magnetic field, also called a solenoid

Solenoid Applications Click on each picture to go to a supporting youtube video Door Bell- Relay Switch- Speaker- http://youtu.be/KqcT-oYImFQ

Motor Action When a current is applied to wire that is in a magnet field the field created by the electron flow causes a force that will repel the wire causing it to move. This is called motor action.

Play Video by clicking on the picture above Electric Motors An electric motor uses the principle of the repelling force to turn electrical energy into mechanical energy. Play Video by clicking on the picture above