Re: [Phys-l] anode and cathode

[John Denker <jsd@av8n.com>]

On 12/03/2006 06:11 PM, Michael Edmiston wrote:

> I certainly agree we are better off not using anode/cathode.  I've 
> always preferred positive/negative and p-type/n-type as you suggest.

:-)

> This is just a minor comment on zener diodes.  Don't we acknowledge that 
> zener diodes are backwards?  In normal use we say they are "reverse 
> biased."  Even if we use p-type and n-type to name the ends we have a 
> problem in the sense that current in a regular diode runs into the 
> p-type end and out the n-type end, but this is not the case in a zener 
> diode used in the usual way.  So it seems to me zener diodes aren't 
> labeled backwards as much as they just are backwards.  That is, whatever 
> "current rules" we set up for whatever names we give the two ends of a 
> diode, a zener diode is going to break the rule.

But ... consider the analogy to rechargeable batteries.

If you make the mistake of attaching cathode/anode labels to
battery terminals according to structure, not function (which
is the mistake the Zener diode guys made), then during either
the charge or discharge phase the labels will be "backwards".

My point is that for batteries we do not tolerate "backwards"
labels.  We change the labels to always reflect function, not
structure.

What's sauce for the goose should be sauce for the gander.  The
rule that applies to absolutely everything I know of including
rechargeable batteries is violated by Zeners.  I continue to
believe this violation is a blunder.