and what happen if the source is ac if v(rms)=320 and f=50hz

 

Okay, at least you've started a new thread, but now you have no context (remember, most people will see this thread in isolation and not know that it has anything to do with a particular other thread) and so the question is meaningless. You should either snag the circuit from the other thread and post it in this one or include a link to the other thread along with a short description of the context, such as, "Another thread asked what happened when the switch on a DC supply connected to an RL circuit was suddenly opened. I'm curious about what happens when...."

Even then, however, your question is completely vague. You can't just swap the DC source with an AC source because now there is the issue of WHEN the switch is opened relative to the cycle of the AC waveform.