Friday, September 23, 2011

On the Investigative Project

We finally (again, FINALLY) finished the formal report and passed it to Sir. It was one of the most difficult things to do this sem, and passing it removed a big chunk of problems off my back.

With all experiments done, we now set our focus on the investigative project, which our group decided on to be the gold leaf experiment, an experiment that displays the wonders of Coulomb's Law and induction.

Compared to the other groups' projects, our experiment seemed to be relatively easy. That is, we were able to finish doing it in one very short session outside class.

Hmm. What more? I think that's about it for this post. I'll tell more about the gold leaf experiment once we've done the paper. It's the homestretch, that is, Physics 102.1 is almost over. I have to get ready for the Practical Exam, which I'm quite nervous about.

Saturday, September 3, 2011

On Resonance in Series RLC Circuits, Part 2

This experiment is the experiment that we would make a formal report of. And I must say, I'm not that enthusiastic about it. Trying to make the lab notebook was almost impossible for me and Mac, maybe because we were kind of rushing to finish it to reach the "submission", but ultimately we gave up due to no prior understanding of AC, lack of time, hunger and "O_O". Unfulfilled and defeated, we went home...

Well, that was last Wednesday.

So, Thursday came and, still, we have not finished the lab notebook. And to add to that, we have not even started the formal report, which was due on that day too. So, it was literally hell on earth that day. I was ready to give up and drop out of college, but when we arrived, we realized that that meeting was not the submission of both notebook and FR, it was next week. That Thursday was dedicated for the other groups to finish the experiment. When those words began to process in my head, it was like an early Christmas for me. School has been very very difficult and tiring and excruciatingly sad for me the last couple of weeks due to the landslide of things to do and low grades, and this "moving" of the deadline was purely good news that was something nice to hear.

Yey. So, now, we really have to work hard on the formal report.:D

On Resonance in Series RLC Circuits

RLC Circuits are really complicated. That was the first thing that popped into my mind when Sir Baldo began discussing RLC Circuits, a circuit involving an AC source, a resistor, inductor and capacitor. As opposed to the topics that we have discussed for the past 6 experiments, the treatment for this one was more mathematically rigorous.

Anyways, at least we did not have a quiz that meeting, due to the fact that lack of time translated to lack of postlab quiz, so a take-home quiz was given to us.

The lecture that meeting was long, I think the longest it has ever been. It was understandable, though, because there are a lot of things that are needed to be tackled to fully describe an AC circuit. Since the voltage provided by an AC source is not constant (unlike DC), the current is not constant too, so normal methods for DC circuit analysis cannot be applied. Here, tools such as phasor diagrams and wave functions (sines and cosines) are used. It's a lot more difficult than DC. But weirdly, it looked a bit more appealing to me than DC. Still, I do not get AC that much because we have yet to tackle it in lecture class (wait, I don't think lecture class is not much help either), or err I have yet to read about it in the textbook. Another new circuit device introduced in class is the inductor, which by what I understood is a device that resists large changes in current by inducing an emf (thus a current) opposite the large change in current. Reactance (X) was also introduced. It was said to be the opposition of a circuit element to a change of electric current or voltage by the capacitor or inductor. Also, impedance (Z) was discussed. In an AC circuit, it acts as the "total resistance", and it can be plugged into Ohm's Law. Impedance, in terms of reactance of the inductor and capacitor, and resistance of the resistor, is:

Resonance of the series RLC circuit was the main thing that was the subject of the experiment. At resonance, the maximum current is obtained, and the frequency that corresponds to resonance is called, surprise, resonance frequency. Also, at resonance, the equivalence of inductive reactance and capacitive reactance is observed, and, due to this, the impedance is at a minimum.

The experiment was quite easy, as opposed to the concepts it showed. Basically, what we had to do was adjust the frequency of an AC source output and observe what happened to the voltage across the source, the capacitor, the inductor, the resistor, and the inductor-capacitor, and also the current across the circuit. We obtained the frequency where maximum current was obtained and called this the resonance frequency. We did this procedure with 1 capacitor, 1 inductor, and 2 resistors, one at a time.

We made use of the whole period and extended a bit, showing how time-demanding the experiment this meeting was. That was basically it for that meeting.

So for my thoughts: This was the first time I was introduced to AC circuits in my life, and I must say, I am a bit confused about it.:S As the semester progresses and we dig deeper into the world of electromagnetism, I get more and more "O_O" (I have no word for it, so I present a face). I really don't think that electromagnetism is my niche in the physics world, mainly because I can't really say I'm excellent at it and that much enthusiastic about it. All I can give is hard work and perseverance, and I hope that it pays off in the end.