# Question about Diode potential of anode with respect to cathode

Discussion in 'General Electronics Chat' started by skyline1397, Sep 13, 2017.

1. ### skyline1397

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If I have an ideal diode and I apply -9 V in the anode (P-type junction) and -10 V at the cathode (P-type junction) would the diode become forward biased??
I get that the current-voltage relationship of an ideal diode shows that as long as the voltage across the ideal diode is non-negative i.e. V≥0, the ideal diode looks like a short circuit but the graphs refer to V. Is this V equal to V(anode)-V(cathode)?
Where V potential of anode with respect to cathode

skyline1397, Sep 13, 2017

2. ### Harald KappModeratorModerator

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Voltage is always about potential differences. What is the potential difference V(anode)-V(cathode)?
A positive voltage between anode and cathode will make the diode conducting.
A zero or negative voltage between anode and cathode will make the diode non-conducting.

Harald Kapp, Sep 13, 2017

3. ### dorke

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Welcome to EP.

You can not apply +1V "on" an ideal diode.
The most possible is 0V,
this will case the diode to conduct ,
the current will be limited by the external resistance.

dorke, Sep 13, 2017
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4. ### Ratch

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You have to have an infinitesimal amount of voltage across an ideal diode for current to be present. Even a copper wire short will not have any current existing at zero volts.

Ratch

Ratch, Sep 14, 2017
5. ### BobK

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Which is why ideal diodes do not exist.

Bob

BobK, Sep 14, 2017

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