Theory issues regarding forward and reverse biased diodes and voltages

Thread Starter


Joined Nov 11, 2012
So far, from what I've studied... Current flows from the positive to the negative. Then here comes diodes, where there's forward-biased, reverse-biased, forward current, reverse current, forward voltage and reverse voltage.

In a DC voltage, isn't there only direction of current flow? Then how would reversed voltage come about in a DC circuit? Should the voltage of a reverse-biased diode be 0? Why is there a discussion of reversed voltage? And what is how does reverse currents work?

Seriously confused kid over here. :( :confused:


Joined Mar 24, 2008
This is a physics forum. We have an electronic chat forum, as well as a project forum, so I am moving your threads over there.


Joined Feb 17, 2009
This imagines explain everything

Forward-biased diode

Reverse-biased diode

Diode allows current to flow in one direction (called the diode's forward direction), while blocking current in the opposite direction (the reverse direction).
Any more questions?



Joined Feb 17, 2009
I add that when diode is reverse biased

Only small reverse current will flow and this current is essentially constant no matter what reverse bias is applied. If reverse bis voltage increased sufficiently beyond reverse breakdown voltage. Diode will begin to pass a large reverse current which can destroy the diode.


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Joined Oct 18, 2012
I think it's important to note for the OP that if he/she looks at the ebook of AAC that it follows the electron path current flow, which is opposite to the conventional current flow as seen above...


Joined Aug 16, 2010
It sounds to me like the OP is just having trouble with terminology.

These terms can be used in other ways, but generally...

Bias means voltage. Forward bias means that the voltage is applied to a device (such as a diode) with the correct polarity for current to flow (positive to anode, negative to cathode).

Reverse bias means that the voltage is applied to the device (such as a diode) with the opposite polarity, such that current will not flow (negative to anode, positive to cathode).

The term reverse current may have bothered you. In the case of a diode, all this means is that with the voltage applied in the reverse bias direction, such that current doesn't flow, there is actually a small leakage current that gets through the diode.