Click HERE to see this thread with all of the graphics, features, and links.

Does Obi-1 think Anakin is dead in episode 3? if so than how does he know that Vader in episode 4 was Anakin? Did he sence him?

no, he knows hes alive

Of course, I think that Obi Wan already senced that Vader was still alive when he was transformed into his mechanical form. Besides, his lightsaber was almost identical to the one, wich he used to fight obi in episode III.

He knows that Anakin is Darth Vader, because he saw the Emperor refer to Anakin with that name on the security holograms. Darth Vader had spread terror across the universe after the Jedi purge, so i think Obi-Wan would of atleast heard his name mentioned at some point after Episode III - or sensed him through the force as some of you said

Sensing....learn to spell gungan ...kidding.

Im pretty sure he knows hes alive.