Resistor & diode in series

Discussion in 'Homework Help' started by madmartigano, Oct 29, 2010.

  1. madmartigano

    Thread Starter New Member

    Oct 29, 2010
    1
    0
    I'm asked to plot current vs. voltage for two circuits: one with just a constant voltage source and a forward-biased diode in series, the other with a constant voltage source, a forward-biased diode, and a resistor in series. All the information I have available for this question I've attached as a jpg. I'm basically having difficulty understanding how adding a resistor in series with a diode will affect the current of that circuit. I'm assuming it must somehow, I just don't know how to model it mathematically. My teacher apparently assumes this knowledge must be self-evident, but I still need someone to point out the obvious to me. Thanks in advance for any help.
     
  2. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
    718
    A resistor limits the current that can flow through a diode.

    Roughly speaking, resistors change a voltage source into a current source.

    This is the reason resistors need to be used with LEDs, they act like 20mA fuses with a ~2V drop.
     
    madmartigano likes this.
Loading...