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I have a simple question from the electronics course If the cut in voltage of the diode is 0.7 find the voltage and current across the diodeenter image description here

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  • \$\begingroup\$ Show your effort in solving this question. Otherwise this seems like a homework problem. \$\endgroup\$
    – Catsunami
    Feb 21, 2018 at 20:33
  • \$\begingroup\$ You need to tell us about your approach. Whatever comes to your mind. \$\endgroup\$ Feb 21, 2018 at 20:33
  • \$\begingroup\$ This is a (homework) assignment without any effort shown by you to answer it. It is OK to ask about homework but you must show what you have tried. Now you leave all the work up to us and we don't do that here. \$\endgroup\$ Feb 21, 2018 at 20:33
  • \$\begingroup\$ It's not even a homework but okay here's what i did: we were not given the forward bias resistance rf so it is zero the vd equals 0.7 , i tried relacing the diode with a battery since it is forward biased but was not sure how to continue \$\endgroup\$
    – Roa'a
    Feb 21, 2018 at 20:41
  • \$\begingroup\$ if Vf is 0.7v, then what's the voltage across R2? And what's the voltage across R1? So what's the current through them both? So what's the current through the diode? Good clear photo of your sketch BTW! \$\endgroup\$
    – Neil_UK
    Feb 21, 2018 at 20:50

1 Answer 1

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  1. Figure out if the diode is on or off.
    (Hint what would the voltage at the diode be if the diode were not there.)
  2. Once you know that, you should know what \$V_D\$ is.
  3. Knowing \$V_D\$ you can calculate \$I_{R1}\$ and \$I_{R2}\$.
  4. \$I_D\$ = The difference between \$I_{R1}\$ and \$I_{R2}\$.
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