Why does a diode have a specific sign?

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Discussion Overview

The discussion revolves around the nature of current flow in diodes, particularly focusing on the conventions of current direction and the implications of electron flow versus conventional current. The scope includes conceptual clarifications and technical explanations related to semiconductor physics and electrical circuits.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why a diode is represented with a specific sign, noting that the current appears to flow from the p-side to the n-side, which seems contradictory to the notion of a short circuit.
  • Another participant clarifies that conventional current flows from positive to negative, emphasizing that this convention predates the discovery of electrons.
  • A participant seeks clarification on whether current is synonymous with the flow of electrons.
  • Further discussion reveals that current is defined as the flow of electric charge, with electrons moving very little while the electric signal propagates quickly through a conductor.
  • One participant mentions the concept of 'holes' in semiconductor physics, which represent the absence of electrons and can flow in the direction of conventional current.
  • A later reply notes that treating current as either positive or negative charge motion yields the same results in practical applications.

Areas of Agreement / Disagreement

Participants express differing views on the nature of current flow and the implications of electron movement versus conventional current. There is no consensus on the best way to conceptualize these ideas, indicating ongoing debate.

Contextual Notes

Participants highlight the confusion surrounding the movement of electrons and the historical context of current definitions, but do not resolve these complexities or assumptions.

Who May Find This Useful

This discussion may be of interest to students and professionals in physics and electrical engineering, particularly those exploring the fundamentals of current flow and semiconductor behavior.

nhrock3
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why diode has such a sign??

2ztbr68.jpg

by the bottom sketch we have the diode to be short circuit

but if we look at the upper sketch we see that the current (ie electrons)
flows from the plus p side

for diode to be short circuit we ned to have the electrons flow to the n side
not to the p side


and i remmember my lessons of basics circuits

they said that the current flows from the big potential to the lower potential
so the electrons move from plus
so if its true the diode cannot be short circuit in that way?
 
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Conventional current flows form positive to negative, current was invented before electrons.
The simple for a diode is supposed to look like a one-way arrow
 


so current is not the flow of electrons?
 


then what flows there?
 


Current is the flow of electric charge.
There are two things that confuse people:

1, electrons don't move (much). The electricity flows through a wire at almost the speed of light but electrons only drift a cm/s. The electricty is more like one electron bumping into the next and pushing it, it then pushes the next one and so on.

2, Current was invented before people knew about electrons and people arbitrarily decided it flowed from positive to negative. This is just a convention - like deciding that North is UP on a map.
Now we have discovered electrons are negative and actually flow from negative to positive there is a small problem. in practice this doesn't matter you can just ignore the electrons and use current, or imagine a negative current flowing from negative to positive.
In semiconductor physics we picture a flow of 'holes' which are imaginary positive electrons (or rather the absence of an electron) which do flow in the correct direction.
 


thanks :)
 
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