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My Diode Question Clarification

So. Ya’ll must be as sick of this topic as I am of thinking about it :).  I wanted to clarify and to posit an answer that for now my brain can wrap around.

So my question was: The question is if current/electrons go from the negative side of the battery to the positive side of the battery, how do diodes only allow current to go from anode to cathode (or P to N)? 

This confused a lot of people (like 6 people that I’ve asked) and they started talking about the depletion zone because I don’t think they read the entire question.  If you only considered the “How do diodes only allow current to go from anode to cathode” question, you’d think that I didn’t know about depletion zones and start explaining.  And I actually do…SO. 

Consider please then the entire question.  Given how diodes function in a particular set up relative to its power source/battery, and that electrons move from the negative side of a battery to the positive side of a battery, how can we say current (coulomb of electrons/second) flows from P to N in a diode when electrons clearly flow N to P? Sub questions that spin off of this then are:

  • What direction does the diode actually block current from?  P or N?
  • When you’re putting these diodes in a circuit, don’t you think of them as blocking electrons from a certain direction?  So which direction do you put them in - backwards?

So first off, don’t let these sub questions confuse you - these are some of the questions I thought of because I was extremely confused.

So I have been told I am referencing TWO different “naming conventions” in the same question - the conventional flow theory and the electron flow theory.  Current only flows from P to N according to the conventional flow theory and current flows N to P according the electron flow theory.  So really, asking that question like that is confusing.  Also the general consensus is that the symbol is in fact written backwards - so I’ll work that in next.

And to address the sub questions, we need actually to take a step back and look at a circuit.  I choose to do it electron flow style.

Okay. So what can easily throw off someone such as myself is the actual freakin symbol (which is known to be backwards).  I personally think about circuits with regards to how electrons/charge flows through them.  So I’m going to change the symbol!

So my answer to this dilemma is to look at it via electron flow instead of conventional flow - and to change the diode symbol so that it doesn’t indicate direction.  The only important thing for diode function is its P-N orientation compared to the power source.

As long as the power source and diode are oriented + P N - charge will flow.

As long as the power source and diode are oriented - P N + charge will not flow.

So when thinking about AC current for example, it’s as if the battery is constantly changing from being oriented + - to - +.  This will make it so that the diode ends up blocking current whenever the battery’s in the “wrong direction”.

I think this solves it? Yes? Hopefully? (Heck it’s my own question and I deem it solved :p)


Filed under conventional flow theory electron flow theory diode how do diodes work tymkrs

  1. tymkrs posted this