You are a double-agent in the most important war of the 20th century, The Falklands war. For years you have been playing the United Kingdom and Argentinian governments against each other, taking bribes from both sides and it has caught up with you.

One day travelling you are snatched off the street, kidnapped, drugged and placed on a private plane. You wake up in a cell, you know you have been taken by one of the governments to their capital for interrogation and treason charges but you cannot tell which has abducted you. You have perfected both the UK and Argentinian languages and accents and you know you can convince the guards to let you go if you were to speak in their native tongue asking for your government contact. However speaking the wrong language first will certainly turn out very poorly for you indeed.

You look around your cell, it is a large room with high ceilings, a musty smell, and thick dust covering everything. Based on being unable to hear anything and the constant temperature you conclude you are underground. Nothing about the architecture is distinctive. The only things in the cell are a single metal chair bolted to the floor in the center of the room with a spotlight hanging from a cord right above the chair illuminating the seat brightly leaving the rest of the room in shadow. You know it is a matter of time before you are tied into the chair and interrogated by shadowy agents of one of the governments.

You search desperately for a clue as to where you are. You kick the chair and stub your toe; it is solid. You claw at the light, looking for a marking or a way to open it and see the voltage rating but cannot find either. You yank and pull on it to test how secure it is and cannot dislodge it from the ceiling to get at the cord. You try to swing it far enough to smash against a wall but it will not reach. You search the chair for a makers mark but can find none. You know much more action will invite suspicion even if you know the right language so you stand back and think.

The guard watching on CCTV notices, but decides it is normal behaviour for someone waking up in a cell regardless of guilt so is not immediately suspicious. As far as he can tell you then pace around the room randomly for a few hours deep in thought.

You suddenly walk towards the door and knock, with 100% confidence you correctly ask in perfect Spanish for your government handler who promptly releases you.

How did you know what government to ask for?

You can assume you are correct in all your assumptions mentioned in the puzzle.
You have no items other than the clothes and shoes you were wearing when abducted. no cell phone, no watch, no pocket lint etc.