As you probably know if you're reading this, I'm doing a part-time Physics A-level at the moment. This means I'm out of the office on Tuesday mornings and Friday afternoons, and I get to do more interesting stuff instead. We've covered most of the theory for the exams now, so today we started on our practicals. Today's involved a black box (marked X), which contained a capacitor and resistor. We had to measure various voltages and currents (DC and AC), to figure out the resistance and capacitance.
So, I assembled the circuit ok, then took readings. I went through from minimum to maximum power in DC, and recorded the voltage and current at each point. So far, so good, although the range of voltages I got didn't quite match what we were supposed to get (they wanted us to go up to 1.4V, and mine went from 2.58V to 14.95V), so I left it sitting there for a while until I could check with the teacher. Roshala (one of the other students) then came over to check what results I'd got for AC, but I hadn't got that far yet. I compared my DC results to hers though, which matched, so I figured I was doing ok, and switched the power supply and ammeter over to AC (still on max power). BANG!
If you've seen "For the birds" (the short film before "Monsters Inc"), you remember the feathers drifting down at the end? It was a bit like that - I was sitting there stunned, while little pieces of insulation floated down onto the desk. Apparently it created quite a bad smell too. The teacher came over (as did most of the class) to take a look, and said I shouldn't have left it on max power for so long. At that point, about five people (including Roshala) went rushing back to their desks to turn off their power supplies! I suggested to her at that point that I might not be the best person to ask for advice, but amazingly she stuck around. Admittedly, I think I was providing sufficient entertainment value to counter the danger :) I was fine, although I'm glad I didn't have my hand near the box.
We've got assessors coming into class next week, so our Tuesday teacher has asked us to turn up on time as a favour to him :) The Friday teacher (today) was saying it was a good thing they weren't here today, as they'd probably be wibbling about Health and Safety issues... I wonder if they'd mark me down for that in an exam.
The thing is, I like this type of thing (building circuits). I find it fun, and interesting. Unfortunately, I'm not very good at it. Hopefully I'll improve with practice...
Anyway, I got new equipment, and finished the experiment ok, and kept the burnt out bit as a souvenir. I'll probably take a picture later.
Edit: Here's a (blurry) photo as promised: