For common emitter configuration of a PNP transistor why is current 0 when emitter-collector voltage is 0?
I think this is the circuit you are asking about because applying an external short circuit is the only sure way to force the c-e voltage to 0 V.







simulate this circuit &ndash; Schematic created using CircuitLab

In this circuit, the collector current is not necessarily 0. If the base voltage, supplied by V1, goes negative by more than a few 100 mV, then the b-c junction will be forward biased and current will flow from the collector to base, producing a positive collector current (under the passive sign convention).