what happens if a voltage source with resistor are being short circuited I will give a concrete example
I would say the voltage Uab in this case is equal to zero ,because the potential between the two points A and B is equal to zero, and the voltage source is parallel to it , so its also equal to zero. I even tried to do source transformation and i got that the current is equal to zero . what I did is right ?
what im interested in in the voltage between A and B or thec current between A and B

 

Hi,

I think you meant "Short Circuited".

If we start with your voltage source and resistor we have:
I=V/R

If we first convert that to a current source we have:
Ia=V/R

With the first circuit if we have an open circuit we just have output:
Vout=V

and with the second circuit if we have an open circuit we have:
Vout=Ia*R=V

If we short out the first circuit we have:
Iout=V/R

and if we short out the second circuit the resistance is zero so we have:
Iout=Ia=I

So yes your circuit looks right.

This was easier because we just had a resistor with the DC voltage source.

 

what can you say about the voltage Vab

 

what can you say about the voltage Vab

Vab=V

 

Vab=V

can you explain why

 

can you explain why

There is no current.