Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Light emitting diode

  1. Feb 13, 2008 #1
    when forward bias of led is increased, the intensity of emitted light increases until it reaches a max after which it starts decreasing again.....why?
    also, in which of the two cases is barrier potential greater, led or pn diode?
     
  2. jcsd
  3. Feb 13, 2008 #2
    pls make u r question more clear... (led is a type of pn diode) so wat do u mean by whose potential (barrier) is greater!!!
     
  4. Feb 13, 2008 #3
    i think he mean the intensity of LED increase as current increase, but then if current goes beyond rated max of LED, why the intensity goes down..??

    http://en.wikipedia.org/wiki/Light-emitting_diode
     
  5. Feb 13, 2008 #4

    dlgoff

    User Avatar
    Science Advisor
    Gold Member

    The light intensity will go to zero if the current gets too high.:biggrin:
     
  6. Feb 23, 2008 #5
    i mean the normal pn diode used in circuits
     
  7. Feb 23, 2008 #6

    NoTime

    User Avatar
    Science Advisor
    Homework Helper

    For single color LEDs (not the "white" ones) the barrier potential is coupled to the light output frequency.
    If you look at the specs you will find that Red, Green and Blue LEDs have different barrier potentials.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?