Help Input output characteristics of BJT

[iampaul]

help! Input output characteristics of BJT

I have attached an image of the graph. Does this graph apply for both npn and pnp transistors. I have asked this because for pnp, the collector(c) and base(B) terminals must be reverse-biased at the active region, and B must be at a higher potential than C. Therefore, i think that for the active region Vcb is negative: Vcb= Vc-Vb <0 so Vbc must be positive. As shown in the graph, the transistor is in the active mode for Vcb>0. Why?

For npn there is no problem. That's why I'm asking whether this graph applies for both npn and pnp. Please reply. Thanks!

 

[iampaul]

i can't attach the pic so i'll jusr give the link
http://comutronics.blogspot.com/2012/02/ece-basic-interview-question-and_06.html

 

[uart]

I have asked this because for pnp, the collector(c) and base(B) terminals must be reverse-biased at the active region, and B must be at a higher potential than C. Therefore, i think that for the active region Vcb is negative: Vcb= Vc-Vb <0

Correct for a pnp transistor.

As shown in the graph, the transistor is in the active mode for Vcb>0. Why?

Presumably because they are showing the graph for a npn transistor.