Transistor basics question

Discussion in 'General Electronics Chat' started by Nathan Hale, Jul 3, 2015.

  1. Nathan Hale

    Thread Starter Active Member

    Oct 28, 2011
    125
    2
    Hello folks! hope all is well.

    I just started learning about transistors. i am following a text book i bought online.
    I am stuck trying to understand an illustration in the text book. The picture of the illustration is below. the picture is about an npn transistor.
    my question is.....why would the electrons bother going all the way towards the positive terminal of the voltage supply "B" ? why wont they take the short route and go towards the positive terminal of voltage supply "A"?

    Thank you for your replies.

    P7030066.JPG
     
  2. #12

    Expert

    Nov 30, 2010
    16,340
    6,824
    Two batteries make two current loops. This isn't about electricity taking the one and only, "path of least resistance". Electricity flows in every path of opportunity in proportion to the total resistance in each path.
     
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  3. Nathan Hale

    Thread Starter Active Member

    Oct 28, 2011
    125
    2

    got it!!..... and thats why in a simple 2 resistor parallel circuit there is voltage across the resistor with the higher value and the resistor with the lower value.
    how did i forget that!
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,045
    3,244
    The electrons going to supply B are caused by B's voltage across the base-emitter junction.
    Without that current the transistor would be off.
    And certainly any current initiated by B in the base-emitter junction, which goes to ground, has to go in a compete path to B and ground.
    Remember all currents require a compete path to flow.
     
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