In common emitter configuration, (output characteristics) when Voltage BC becomes negative (change its polarity) then what is the effect on Voltage CE?
You need to stare if it is a NPN or PNP but I will assume NPN.
The base is typically more negative than the collector.
The critical value is the base emitter voltage, which should have the base 0.7v or greater than the emitter for current to flow CE…