Can you add voltages in parallel if you use diodes?

[toneboy1]

I'm sure you can't but I don't really see why not. Its been ages since I've done anything like this and I just wondered, I can't think of a way to varify it like I don't think you can use superposition theorem.

My question is shown in tha attatched picture.

Thanks very much.

 

[I_am_learning]

you will get 6V because the top diode will be reversed biased.

 

[toneboy1]

Ofcourse! Simple and beautiful explanation.