current direction

Discussion in 'General Electronics Chat' started by pjax, Dec 21, 2010.

  1. pjax

    Thread Starter New Member

    Dec 21, 2010
    a npn transistor contain two n-tpyes and 1 p-type. current is a flow of electrons. Like poles repel while opposite poles attract. the n-type consist of excess electrons while the p-type consists of holes(created by electrons moving out of place, leaving a positive electric field). a battery consists of a positive and negative electric field. Knowing all this can some help me figure out how does current flow: from base to emitter; in this case of forward-bias, since the base has a higher potential than emitter? In the case of emitter and collector, if the there is a forward-bias, what direction does the current flow in: from collector to emitter or emitter to collector?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    I suggest you start with our Ebook -

    A battery uses chemical energy to move charges around inside to make the terminal positive and negative. A doped PN junction is a different animal entirely. The energy to move charges comes form outside the structure.

    For a silicon NPN transistor, raising the voltage about 700 mv above the emitter will provide enough energy to promote current, which will be electrons from the emitter to the base. While conducting, the electrons will pass out the collector, bringing it's positive potential down towards the emitter's.