Saturday, December 17, 2011

On Resonance and Sound

In contrast to our experiment last meeting (Calorimetry), we performed an experiment regarding waves this week. Specifically, we performed an experiment which demonstrated resonance, the increase in amplitude of vibration of a body due to the constructive interference of the driving force of the vibration’s frequency and the body’s characteristic frequency of vibration.

Using a resonance “tube” filled with water and a speaker of constant frequency on top of the tube, we looked for the water levels wherein the sound volume was at a maximum. These water levels correspond to the length of the tube that allowed standing waves to be set-up. Also, at these water levels, resonance was observed. By getting the average of the difference between the distance where resonance was observed, we were able to obtain the wavelength using ΔL=½λ. Finally, using v=fλ, we obtained the speed of sound in the tube.

The experiment was quite difficult because it required us to hold the speaker manually above the tube. It was tiring so we took turns doing it. Also, water from the tube unfortunately spilled on the floor which caused quite a mess. Apart from these, I thoroughly enjoyed the experiment because we had good group dynamics.

Saturday, December 10, 2011

On Heat and Calorimetry

Entering the 103.1 lab, I saw a gas stove set up. Asking what it for, I found out that we would be performing an experiment on Thermodynamics.

I consider Thermodynamics to be my favourite subject in our General Chemistry courses (16 and 17). Unfortunately, I have forgotten quite a deal on the said subject, so it was nice to rekindle my interest in thermodynamics by performing a simple calorimetry experiment this meeting.

Basically, what we did was mix hot and cold water together and measure the enthalpy change (ΔH=mcΔT) to see that the heat lost by the hot water and the heat gained by the cold water were equal. It was quite an easy experiment, though numerous little niggles cost us time. For one, the balance used to measure the mass of the calorimeter was in the other room so we had to go back and forth between rooms (though this was remedied eventually), and a short brownout occurred which we had to wait out to be able to use the balance.

Overall, the experiment was quite a simple task to perform. Compared to the experiments in 102.1, this experiment was a walk in the park.

Sunday, December 4, 2011

On Light Intensity

The second experiment we performed was all about light intensity. To cut the story short, it was a quick experiment, not taking up more than 30 minutes. It was a relatively easy task--- we simply measured the light intensity from a light source and a laser at different distances from the light source using a light sensor connected to labquest.

From the graph of light intensity vs. distance from light source, we observed an inverse square law; that is, the light intensity is inversely proportional to the square of the distance from the light source. This conclusion was obtained using data from the light source (not laser). The data we got from the laser showed that light intensity was constant even at great distances. It could probably be the case that the intensity from the laser was so high that very great distances would be called for to see the inverse square law.

We encountered minimal error, if none. I think our group had good dynamics because we finished the experiment in record time. I hope that the next experiments are going to be as easy as this, so that we would always finish ahead of time. :D

On the First Meeting: Physics 103.1

Now that Physics lab meetings are on Mondays for this sem, I don’t think I’m going to be as stressed as I was last sem. I think that it is a good idea. Anyways, let me narrate what transpired on our first meeting.

The first Physics 103.1 meeting was quite “chill”, for lack of a better word. We didn’t perform any experiment or any hectic task. What happened, though, was Sir Baldo telling us the new things in store for us--- the experiment reporting (in lieu of the quizzes we had last semester) and the consequences for late submissions. Also, he shared to us some info about our lecture professors.

This was also the meeting where we finalized the groupings for the experiments. For Physics 103, my groupmates are Mac Aydinan, Reggie Bernardo and Julia Negre. Overall, I think that it is an excellent group. I don’t think communication is going to be a problem at all.

I’m quite excited for Physics 103.1, primarily because there are no circuits (which I hate) involved in this lab class (I think).

Sunday, November 27, 2011

On Optics and Ray Box Experiments

Our first Physics 103.1 experiment dealt on a very interesting topic- Optics. I, for one, was quite excited about it because I didn’t really have much exposure to said topic in the past and I was enthusiastic to learn about it. After receiving the instructions and data sheet from Sir Baldo, my mouth dropped because of the sheer length of the experiment. It was EXCRUCIATINGLY long- composed of six “mini” experiments. Topics included color addition (where we added RGB colors using a ray box), refraction (where we learned that it was merely the bending of light and that it governed a principle called Snell’s law), reflection (where we twirled a mirror around to see what would happen to the rays hitting it), total internal reflection and the determination of the index of refraction using Snell’s law. Overall, the experiment was very tiring. Even for a group of 4, the experiment took a whole meeting to accomplish.

The first meeting was quite a “new world” for me-- well it’s to be expected coming from Physics 102.1 which was all about electric circuits. Well, it’s a sign of relief because I never really warmed up to it.

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.

Sunday, August 7, 2011

On Electromagnetic Induction

Ok. This might have been the worst possible meeting to be late, and unfortunately, my friend Mac and I were. Because we had to finish our summary report, we were around ~25 minutes late, and the post-experiment quiz was almost over. Thank God Sir was kind enough to let us answer the whole quiz, but, still, I think that my grade in that quiz is low. I was quite clueless during the quiz, with sweat dripping because we were running before we entered the classroom. I just hope that I passed the quiz.

What's done is done, so let's move on.

Our experiment this meeting was all about electromagnetic induction. What this phenomenon means is that changing the magnetic field around a wire induces a current and emf in it. By Faraday's Law, this induced emf is equal to the negative time derivative of magnetic flux. By Lenz Law, we can note that the direction of the induced emf or current is in the direction opposite the cause of it. Therefore, if a magnet (N pole facing the coil) is put nearer to the coil, an emf and current will be induced in the counterclockwise direction, since the coil will resist the magnetic field on it due to the magnet by producing an upward magnetic field itself.

The experiment proper was quite short, because it only involved one set-up (solenoid) with different 'twists'.

This meeting introduced us, physics students, to a new measuring device ---- the GALVANOMETER. From wikipedia, a galvanometer is a type of ammeter that produces a rotary deflection of some type of pointer in response to current flowing through its coil. Using the galvanometer was the first part of the experiment. Here, I also learned (from the handout) that humans are considered large resistors. :O

We, then, looked at the effects of probing a moving magnet at the hollow part of the solenoid. It was observed that the faster the magnet was "swiped", the higher the magnitude of the deflection on the galvanometer. When it was put into the solenoid, the deflection was to the right. When it was pulled out, the deflection was to the left.

We, then, put different metals (iron, copper, aluminum) on the hollow part of the solenoid. We saw how the magnets affected the deflections on the galvanometer, and I think that it has something to do with the types of magnet because each of which was of a different type (ferromagnet; diamagnet; paramagnet).

Lastly, we looked at the effects of putting a smaller solenoid in the middle of the solenoid, and withdrawing the smaller solenoid a centimeter at a time until it was completely outside. This was the part that was quite a source of confusion because the procedure dictated that we had to start at the point when the smaller solenoid was completely inside the solenoid. There was some space between the two solenoids that was not accounted for, but we figured it out.

This experiment was relatively easy because it was quite straightforward. Compared to the past experiments that we had, this was one of the quickest to be accomplished.

Lesson learned today: don't be late. I want to repeat it to myself. Don't be late.

Sunday, July 31, 2011

On the Sources of Magnetic Fields

The topic this meeting is far far ahead of the topics that we have in Lecture class, so everything was quite new to me (but thinking about it, I don't think I'd learn anything in Lecture class if we discussed this :|). So basically, this meeting was all about the sources of magnetic fields, of which there are a number of.

The first source is permanent magnets, or the objects that naturally have a magnetic field associated with them. Basically that's it for permanent magnets.

The second source is the motion of charged particles, which is given by the equation:

where B=magnetic field vector, v=velocity vector, mu-knot=permeability of free space, q=charge of the moving particle, r=unit vector from position of particle to point where B is measured

This complicated equation basically says that the magnetic field is the cross product of the velocity and position vector wrt to where it is being measured times a constant given by the other terms. This means that there is no magnetic field when the velocity and position vectors lie on the same line (cross product is 0) while it is a maximum when the two vectors are perpendicular.

An extension of this source of magnetic fields is a current carrying wire. I won't put the equation anymore because I can't find a picture of it in Google, but I would say that the equation is quite similar in form to the one stated above.

Another source is a very long solenoid. When I first heard of this word, I was quite clueless of what it is. I previously heard of it in Physics 111 when we were discussing the divergence of a vector field. It was said that a solenoidal vector field is one that has 0 divergence at all points. I had no idea of what it meant, and still no idea at present. :| What I do know is how a solenoid looks like. It's basically a wire curled up to resemble a compressed slinky. This source of magnetic field also has an equation associated with it. Here:

Okay, I now want to talk about the experiment that we performed. Just like the other experiments that we had, this experiment is also a series of 'mini' experiments about the sources of magnetic fields.

The first mini experiment that we performed was measuring the magnetic field at different points around a permanent magnet (horseshoe and bar) using a magnetic field sensor and labquest. Honestly speaking, this part was quite arduous because the measurements were quite erratic and we had to take a LOT of measurements.

Then, the next thing that we did was to measure the magnetic field from the center of a horseshoe to the outside part of the horseshoe. Okay, that was quite confusing. Basically, we measured the magnetic field as a function of distance from the horseshoe.

We, then, proceeded to perform the next mini experiment. Here, we made use of iron fillings placed on top of a folder. Under the folder, a horseshoe magnet was used, and the iron fillings aligned themselves according to the magnetic field produced by the magnet. It was quite cool because it was like magic.

We were supposed to do Oersted's experiment. Well, actually, we did but it failed. So we had to scrap it off from the procedures list.

Then, we did the final mini experiment, which was to measure magnetic field outside a solenoid which carried a current. We, then, implemented different core materials and looked at how it affected the magnetic field.

... So that's all that we did this meeting.

The experiment was very long and tiring. We were there by 1 and ended at 4, making use of the full 3 hours this meeting. Initially, I thought that the experiment would be fast. But, boy, I was wrong. I haven't fully grasped the concepts of magnetic fields, so I don't know if our data makes any sense. Well, hopefully they do.:))

It's amazing how people (physicists) discovered how magnetic fields work, and even derived equations that explain how they occur. I'd never had known any of these if I didn't enter Physics.

I was also amazed by the device Labquest. I want one for my own.:D

Sunday, July 24, 2011

On Kirchoff's Rules and Capacitors, the Return

The whole meeting this week was dedicated to answering a relatively long quiz about our previous two experiments.

The quiz was implicitly divided into two parts: one on Kirchoff's and the other on capacitance. The first set of items on Kirchoff's Rules were quite easy, because it just demanded from us knowledge on how to use the equations of Kirchoff's Rules. But it was a bit of a struggle for me to get the right answer because of wrong arithmetic. Roar.

The second set of items on Kirchoff's Rules required of us deeper thinking. And this is where I was sweating bullets because it was quite difficult.

The capacitance part of the exam was easy, relative to the part on Kirchoff's Rules. We were given the equations of the charge and current. The only thing that we needed to do was to plug in values. :D

Needless to say, this quiz was a challenge for me, but what made it tolerable was the fact that Mac helped me out and that Sir Baldo was there, available if help was needed.

After the exam, Sir Baldo returned to us our lab notebooks. He told us that we were given a chance to revise our not-up-to-par lab notebooks so that we would have a higher score. :D

Thursday, July 21, 2011

On Trials and Tribulations

My blog post this meeting is short, primarily because we didn’t conduct an experiment.

Anyway, this meeting was dedicated solely for reviewing the coverage of our long exam (which by now is already two days past). Needless to say, the review was very useful and informative. Some selected items in our problem sets were answered live by sir, which made me go “ah” a few times because of the fact that some items were easier watching being answered than answering them myself. Sir was also kind enough to provide a copy of the answers to us. Thanks Sir! ^_^

Some thoughts on the exam:

ü The exam was excruciatingly HARD. (I don’t know if others had a hard time as well)

ü I think I failed the exam.

ü I hope the checker is generous in giving partial scores.

I guess I’m not really cut out to be someone great at electromagnetism. One exam down, three more to go. I hope I don’t fail the other exams.

Saturday, July 9, 2011

On Kirchoff's Rules and Capacitors

This meeting was quite hectic because two activities were scheduled to be done by 4 pm so that we wouldn't have to perform any experiment next meeting, and we could just review for our long exam in 102, which I consider my impending doom.

Anyway, the lab meeting started with a lecture on Kirchoff's rules and Capacitors, two very new concepts for me. Because of the possible lack of time, the quiz on these topics was postponed to next next week (yey!).

So, the first topic for the lecture was Kirchoff's rules, which are basically two rules on how to simplify measuring current and voltage in a DC circuit.

The first rule, the junction rule, states that "the algebraic sum of the currents at any branch point or junction in a circuit is zero." This rule fortunately conforms to common sense, so "getting" it isn't really that hard. For example, in the situation where a junction connects three branches and two currents (I1 and I2) are flowing into the junction, th
e current flowing out of the junction is I1+I2. Basically, the junction rules says that the sum of the directed currents in a junction is equal to 0. It is, in disguise, the Law of Conservation of Charge.

The second rule, the loop rule states that "the algebraic sum of the potential differences around any complete loop in the network is zero." This is a bit more difficult to grasp qualitatively than the junction rule, nevertheless, it's still a lot easier to understand than the things we learn about in 102 and 111. To put it simply, the voltage input and output must equal zero for any loop in the circuit. After reading a bit about it in University Physics, using the loop rule seems a bit complicated when the loop involves a lot of circuit elements.

The second part of the lecture was about capacitors and capacitance, a new addition to 102.1's ever growing collection of circuit elements.

The marking C is the capacitor in the circuit, and the unit of capacitance is farads. Before going in deeper on capacitors, let me first define it. Capacitors are devices which can store charge, and capacitance is just the measure of how much charge a capacitor can store. The amount of charge stored is determined by
where Q=charge, C=capacitance, V=voltage

The capacitance C is given by another formula:
where E=permitivity of free space, A=area of the plate of capacitor, d= distance between capacitor plates

When there is an insulator between the plates of the capacitor, the capacitance C becomes:
where k is a constant of the insulator that is very much greater than 1

We, then, described the effective capacitance in series and parallel circuits. For series, the capacitance formula is equivalent to that of the resistance formula for parallel circuits. For parallel, the formula is equivalent to that of the resistance formula for series.

The charge obtained by the capacitor and circuit current, as functions of time, was derived via integration. The formulas are:
q(t)=CV(1-1/e^(t/RC)) ----> charging (charge)
i(t)=V/(Re^(t/RC)) ----> charging (current)
q(t)=Q/e^(t/RC) ----> discharging (charge)
i(t)= -Q/RCe^(t/RC) -----> discharging (current)

Wow, those were a lot of formulas.:o

Anyway, we started doing the experiments after the lecture. The first we performed was the experiment on Capacitors. The first thing that popped into my mind when I saw the capacitors was that they seemed awfully familiar. I remember very vaguely that we handled capacitors in HS, but I do not know what we did with them.

The experiment on Capacitors was basically a string of activities that, in one way or another, displayed the wonders of capacitors. I do not want to go much into detail but as an outline, what we did are as follows:
  • dissected a capacitor (which was quite difficult)
  • measured the capacitor's capacitance (with the ever-powerful multimeter)
  • measured the capacitance for series and parallel combinations
  • made an experiment that proved the equation Q=CV
  • energized a capacitor and connected it to a voltmeter that was connected to a computer and by using labpro (which was cool), graphed the time vs voltage plot
There was a lot of sources of confusion for this experiment. One of which is our lack of knowledge on capacitors. I, for one, do not know a great deal about capacitors, and I consider myself an amateur when it comes to circuits. The last mini activity was confusing because there was a lot of things involved, and the procedure stated in the activity sheet didn't really go much into detail of what we were supposed to do. Thank God Sir was there, kind enough to help us out.

Lab Pro was really cool because it not only allowed us to get the graph of time vs voltage, but it also allowed us to get a best fit curve of the graph. For the first part of the graph (charging up until the capacitor was fully charged), the graph resembled an inverse exponential function. For the second part of the graph (after turning off the power supply/ discharging the capacitor), the graph resembled a natural exponential function.

By 3:40, we were done with the Capacitor experiment. With only a few minutes left until 4:00, we had to rush the Kirchoff's Rules experiment.

Around this time, too, I saw who I thought was Mikaela Fudolig entering the room looking for our instructor. I was :O and very starstruck (Mac was too) because Mikaela Fudolig is amazing. Having that high of a graduating GWA (1.099) at a young age (16), with her course being Physics to boot, I consider her very inspiring and cool.

I digressed. So, back to the experiment. It was quite a short experiment. We just set up a circuit given a diagram and just measured the voltage, current and resistance. By using Kirchoff's rules, we then solved for the current passing through each element... actually, we didn't do the last step there because it was already past 4. So, we just did it at home.

These two quickfire experiments were quite difficult for me because it required of us to be fast workers, so that we would finish by 4. Knowing myself, my motto in these kinds of experiments is 'work slowly, but surely'. Needing to finish 2 experiments in a span of 2 hours, my motto was thrown out of the window.

It's nice to have groupmates that are very much knowledgeable on circuits. After class, I can ask things that I did not understand during the course of the meeting. For example, using the breadboard was still quite vague to me. I can ask help from Mac after class and after that, I'm enlightened quite a bit.

So, I plan to read on the topics that we have discussed and will discuss, and hopefully by next next week, I will be a master of circuits. :D

Sunday, July 3, 2011

On Resistance and Resistors

For the first time of the semester, Mac and I were late in Physics 102.1. We had to finish the paper and make the final touches so that it would be great, but it seemed that time eluded for me and my group mate. Being tardy was quite saddening because of one reason stated later in the blog, but at least it imposed on my mind the mentality that I should NEVER be late again for 102.1.

So, for the aforementioned reason, when Mac and I entered the classroom, class had already begun and two questions in our prelab quiz were already given out. When I found out about that, I panicked because two questions in, the thoughts of failing the quiz lingered in my mind. I am not good at circuitry, and even if I studied the snippets of info on resistance in our guide sheet, I don't think I "got" what I had to know for the quiz. Thank God Sir Baldo made the quiz do-able. I only managed to get a 6/10 because I exchanged the relationship between I(total) and I(in the circuit) between series and parallel circuits. These activities (and attendance etc.) constitute 5% of our grade, so I need to up my game when it comes to these quizzes to get a decent mark... So no more being late for me!:D

The experiment this meeting was basically a compilation of "mini" experiments focused on the concepts of resistance, and consequently, resistors. Resistance is basically the ratio between voltage and current, as stated in Ohm's Law R=V/I, or in layman's terms, the measure of opposition to an electric current. Resistors, on the other hand, are devices that provide resistance to a circuit. The resistance of a sample (resistor included) is given by the equation:
where: R= resistance, p= resistivity, L=length of sample, A=cross sectional area
It was also stated that resistivity is temperature dependent. That is, at higher temperatures, resistivity increases, thus, the resistance of a sample increases.

I am not going to go into the details of the experiments that we conducted but simply give a breeze-through of what we did and what I thought about them.

The first thing we did was to measure the resistance of ceramic resistors via their bands and comparing it with the values that we got when we measure their resistance via an ohmmeter. This activity was very easy because it just required basic reading skills and simple arithmetic. To add to that, we did this in High School, which I really can't say regarding the other activities that we performed.

The second thing was finding out the schematic diagram of a resistance box. Initially, we thought that the circuit was simply a series because removing we didn't really understand how the mechanism worked. After consulting with Sir, we found out that removing the plugs actually increased the resistance and thereby there were resistors looped around each plug. It was very confusing for me because my knowledge on circuits is rusty. And the next activities just proved that more.

The third and fourth things were to find out the maximum resistance of a rheostat and a variable resistor. Initially, we thought that the rheostat increased its resistance with increased force of push.Regarding the variable resistor, we had no idea. Again, with consultation from Sir, we found out that the position of the sliding thing on the rheostat dictated the resistance because it served as a shortcut for the current to get to the other side. For the variable resistor, the same idea was concerned, though it was still confusing for me.

The fifth thing was measuring the resistance of two resistors connected in series and in parallel. This activity made use of a breadboard, and it was the very first time I've ever seen something like it. I was O_O when I saw it because I didn't know such a thing existed in this world. So, we put the resistors on the breadboard and took their resistance. We, then, solved the theoretical resistance using the bands and Ohm's Law. There was little percent error associated but they were small enough to be ignored.

The last thing that we did was circuit analysis for both ohmic and non-ohmic cases. Here, we made use of a power supply to give out voltage and an ammeter to take the current reading.For the ohmic case, we just made use of a ceramic resistor. For the non-ohmic case, a tungsten lightbulb. The obvious difference between the two cases is the pattern of the data. For the ohmic case, it was very much linear, but for the non-ohmic, the pattern was a bit eccentric but the trend was also increasing.

Admittedly, I wasn't really that useful this meeting because of my lack of knowledge on the topic. I know that it's my responsibility to know about the subject matter beforehand, but this week was very busy for me to fully prepare. To add to that, our Lecture class isn't really helpful at all because the lessons there are far behind the subject matter in Lab. It could possibly be an advantage because it implies that I would be prepared for the future topics in Lecture because we have already taken up in class.

As time goes on, I am beginning to realize that I am more of a mathematician than a physicist. It's very hard for me to grasp the concepts of electromagnetism because I can't imagine stuff that well, but numbers and equations make sense to me. Still, I want to continue on with Physics because maybe I haven't really exerted that much yet to "get" the topics. I think I can succeed if I try harder... And that is I being optimistic.

Saturday, June 25, 2011

On Electric Potential and Electric Field

This meeting marked the first laboratory experiment for the subject.

Prior to that, though, we had the chance to chat with our lab instructor, CK Baldo, since the Physics 72.1 class was not yet finished. I appreciate moments like these because the atmosphere during these times is light and not stressful. It also helped me ease up a bit because I was quite nervous for the experiment considering that I am not a master of electromagnetism by any means.

After that, we transferred rooms and grouped together. My group, composed of myself, Mac Aydinan and Third Garcia, I must say, has good dynamics. Mac and I were lab partners last semester in 101.1 and I think that turned out well. With regards to Third, I haven't really gotten to know him that well because this is the first time that the two of us are classmates in a small class.

Before starting with the experiment, we had a prelab quiz. I had a preconception that the prelab was about the experiment at hand, but I soon found out that my preconception was wrong. The quiz was about electromagnetism in general, zooming in on point charges and electric field. There I was, panicking, because I was unsure of all of my answers. Thankfully, I managed to get an 8/10.

The experiment this meeting is entitled Electric Potential and Electric Field. To be honest, I really do not know the formulas and specifics of these two because of my weak background in this field of study. But still, as an aspiring physicist, I have to, at the very least, familiarize myself with it and, if I am done with that, learn it by heart.

For the specifics of this activity, we had to put two electrodes(spherical and line) on two sides of an electrolytic tank (which is basically a tray filled with water). Then, we grounded one electrode and connected the other to the positive terminal of a battery. We took the voltmeter readings of both electrodes and got 0 volts and 8 volts respectively. Then, by using a probe, we plotted the equipotential lines of 1 volts to 7 volts.

I think that the goal of the experiment was to show that charged objects emit electric fields and that the shape of the objects have an effect on the electric field distribution. It also showed that the electric field lines and equipotential lines are perpendicular and the reason behind this is that to move around an equipotential line entails no work done and for this to occur, the electric field must be orthogonal to it at all instances.

I learned a lot of things from this experiment. First, I learned the notion of the electric field. All charged objects emit an electric field (which when positive is directed away from the object and when negative is directed towards the object). This vector quantity (E) is equivalent to F/q. Another term I learned is the electric potential V. This quantity is electric potential energy divided by charge and is dependent only upon location in the electric field. Around a charged body is a set of curves called equipotential lines. These curves, from their namesake, are curves that have the same potential at any point. These are also perpendicular to the electric field lines. The concept of this orthogonality is not necessarily new because we discussed the occurrence of orthogonal trajectories in Math 54.

After surviving through this first experiment, I realized that I have a LOT to learn to survive the semester. But I do think that I can make it through alive if I study hard and think optimistically.

On a Fresh Start: Physics 102.1

Fresh from the challenge that was Physics 101.1, I am, at present, thrust to a bigger and more formidable challenge.

Physics 102.1, Lab for Electromagnetism, is something I'm quite scared about primarily because I barely know anything about the subject at hand. I'm planning to take all the lessons in strides and just enjoy the ride. Que sera sera.

Saturday, April 2, 2011

The End.

After the last lab meeting, two very important events followed.

The creative work presentation was the first of the two. This entailed that, as a group, we had to present in front of a panel the experiment that we decided to perform as part of our creative work. I, being someone that is not really comfortable speaking up front, was very nervous throughout the presentation. Fortunately, my groupmates were very adept at public speaking, supporting me when I needed help. Overall, our presentation, I think, was above average. Even if we didn't really showcase our best in this experiment, we made do with what we had.

The practical exam followed. This exam was very difficult for me. Unlike the other exams in NIP, this exam was not of the multiple choice variety. I hope that I did well enough to pass.

I have a few regrets for this subject but I don't really have to mention it here. To wrap up this blog, I just want to acknowledge this class as something that taught me to be more responsible. This class made me realize that being a physicist is not easy, yet the rewards in the end are quite fulfilling.

Sunday, March 20, 2011

On Survey Forms and the Final Lab Meeting

March 18, 2011; 8:30-11:30; NIP R108

Today was the last official lab meeting since classes would end next Tuesday. This meeting, we were quite chill because we didn't have to perform an experiment- we just had to answer a set of surveys documenting our satisfaction with the lab course in general and also the things that we learned in the duration of the course.

He also gave us a calculus evaluation which I found pretty useful. Considering that our final exam for Math 53 is next week, the evaluation opened my eyes that I have forgotten a great deal about differential calculus.

Sir Pacho also told us the itinerary for the following week- our creative work presentation in front of the panel and our practical exam. I,for one, am quite nervous for both of these tasks primarily because the two have a big impact on our final grades. Considering my performance for the whole semester, I don't think that I have performed as well as I could.

I learned a lot from Physics 101.1, particularly the topics about error and scientific paper writing. It made me realize how hard it is to write a formal paper given limited time. Overall, this course was challenging yet rewarding at the same time.

Sunday, March 13, 2011

On Densities and Archimedes' Principle

March 11, 2011; 8:30-11:30; NIP R108

This meeting marked the day of our special project wherein we decided to perform an experiment on fluid mechanics, specifically an experiment goaled at measuring the mass of a lemon and a block of wood by noting the buoyant force they give when immersed in three different liquids, namely, water, alcohol and cooking oil.

The first thing that was done was to measure 100 mL of each liquid in each beaker and noting the mass that the liquid contributed. The mass divided by 100 mL constituted the density of the liquid. After which, we measured the theoretical masses of the lemon and block of wood. Then, we immersed the two objects in each medium. We noted the volume of liquid displaced and multiplied it by the calculated density of the fluid. This was the density of the object at hand.

Archimedes' principle states that when an object is fully or partially immersed in a fluid, the fluid exerts an upward force equivalent to the object's weight. This principle served as the basis for our experiment, and we actually tried
to immerse three different objects, the other one being a chunk of styrofoam. Unfortunately, the styrofoam was too light to exhibit a nonnegligible volume of liquid displaced. We needed more precise measuring tools.

I had a very hard time speaking this meeting because of two big canker sores in my mouth, which caused me to be really uncomfortable the whole meeting, actually the whole day. Apart from that, it was also during this meeting that Mac and I were reunited with Peter. The three of us were quite efficient as a group, each member having a definite role to perform.

Admittedly, I was really confused with the concept at first, since fluid mechanics isn't (and I think never will be) my forte. Still, I performed my part and got it all together in the end. The experiment was smooth sailing and we finished ahead of time.

Sunday, March 6, 2011

On the Special Project

March 4, 2011; 8:30-11:30; NIP R108

We were late this meeting, thereby our promise that we wouldn't be late this meeting was broken.

There were no experiments performed this meeting nor there was a discussion of some sort. Our primary goal this meeting was to think of an experiment that we would perform next week that would demonstrate our knowledge on the topics of 101.1.

It may seem easy at first, but, really, it's not. One of the most difficult things for me to do in a science class is to think of some novel idea/experiment. This problem is rooted back in HS wherein we were supposed to think of something like this every year. Seldom did I think of something immediately; I needed some assistance from my teacher when thinking of an experiment.

Here in 101.1, the experiment was to be performed as a group, therefore I would be accompanied by bright physicists that would possibly concoct something great in their minds. After incessant brainstorming, one group member suggested that we do an experiment on fluid dynamics- finding the density of an object by immersing it in an oil and water solution by pressure analysis.

It was really awesome that Sir Pacho accepted the idea because we were the last group that did not have an experiment yet.

I am really happy that no technical paper is needed next meeting, therefore it would be a sure thing that we wouldn't be late.

Sunday, February 20, 2011

On the Center of Mass and Torque

February 18, 2011; 8:30-11:30; NIP R108

For the nth time, we were late this meeting because we had to finish the technical paper. Fortunately for us, though, the experiment this meeting was not really that demanding. We finished quite quickly and made up for the lost time brought about by us being late.

The goal of the experiment this meeting was to calculate the mass of a meterstick in a set-up wherein the meterstick was suspended from a height and was supported in its fulcrum point. We first had to determine the meterstick's center of mass (the point where mass is concentrated) by finding the right spot in its body wherein the meterstick, being suspended mid-air, was balanced. After that, we changed the fulcrum point and added weights to both sides, then carefully finding the positions of the weights that would balance the meterstick. We performed this part two times and took the average.

The mass of the meterstick could be calculated by equating all the torque (clockwise and counterclockwise) to 0, since the whole set-up is in equilibrium. The only missing term in the equation is the mass, and it could be derived with simple algebra.

Using an electronic balance, we measured the true mass of the meterstick. To our pleasant surprise, our calculated mass was only off by less than 1 percent.

After this, we were tasked to make the mass of the meterstick nonuniform - which was done by placing a weight on it- and then calculate the mass of the meterstick+weight by adding weights and by equating the torque with the aforementioned condition (torque=0). We only performed one trial because we were quite confident of our calculations. We, then used the balance to calculate mass, and once again, we were only off by less than 1 percent.

My friend and I made a promise that we would not be late next meeting. In turn, it was also a promise that we would not rush our technical paper and cram the night before.

Sunday, February 13, 2011

On Harmonic Motion and Pendulums

February 11, 2011; 8:30-11:30; NIP R108

Because I was quite late this meeting, it was quite disorienting to see my other labmates already starting a new experiment as I entered the room. The setup that I chanced upon seeing involved a stand, a pendulum, a set of weights and a string. Immediately, simple harmonic motion entered my mind - this week's experiment was all about pendulums. It was something very familiar to me since I already did a variation of this experiment back in High School.

Mac and I formed a new group, since both of us were late. Peter, our other group mate, was absent this meeting. We went upstairs to the physics instruments room to get the setup and what greeted us inside the room was a very upset and grumpy man who handled the materials. I don't want to rant about the old man but it seemed as if he was grumpy for no apparent reason. It irritated me a bit as to how he acted- it was unethical, yes, and also quite unnecessary.

After getting the materials, we went back to the room and started the experiment. Basically, what we were supposed to do was to vary the length of string, angle of displacement, and weight of bob one at a time to see their effect on the period of oscillation.

Since there were only two persons in our group, both of us had to do something. Mac measured the period of oscillation, while I fixed the angle of displacement and released the bob. Like all the other experiments that we have performed, this one was very routinary and involved trial upon trial.

The motion of a pendulum could be described by a mathematical equation:
where T=period, L=length of string, and g=gravitational acceleration.

As we can see from the formulation, the only major contributing factor to the period is the length of string. Their relationship is direct- increasing L increases T. After some research, I also discovered that T is also affected, to some extent, by the angle of displacement, i.e. the equation only works for small angles of displacement. For large angles, more complicated mathematical formulations that involve Taylor expansions and infinite series are required.

The data that we gathered, as far as I can remember, are not that concise with the theoretical expectations. We measured slight increases in period of oscillation as we increased the mass. This could be attributed to error in release of bob or in measurement of time.

Since we were late for the meeting, we were unable to test the scenario wherein the length was very, very high, thereby we had to merge with Robby's group to share with their data. It was very fun because the setup was too big for R108; we had to go to the second floor and hang the pendulum from that height. Admittedly, the setup was quite dangerous since the bob could fling from the string and hit bystanders, but still, it was very fun. For this setup, I was assigned to measure the period of oscillation.

I prefer this experiment to the two previous projectile motion experiments because
1. I was reunited with my old group, even if the other member was absent
2. I was more useful in this experiment
3. the setup was generally more fun (particularly the large L setup)

This new experiment implied that we had to, again, submit a technical report next meeting, something that I'm really not that enthusiastic about.

Friday, February 4, 2011

On Projectile Motion, Part 2

February 4, 2011; 8:30-11:30; NIP R108

This meeting was basically another one devoted to experimentation concerning projectile motion. This time, we were tasked to measure the y-component (height) of the projectile as we vary the x-component (range) while, in turn, varying the angle four times (0, 15, 30 and 45 degrees). This was arguably an easier task since the ball (projectile) was flung to the wall, therefore it did not go to far-off places like last meeting.

If we know the x and y components and the angle of the projectile, its initial velocity could be computed. From my last post,
We know X, Y and A, therefore the only missing term in the equation is the initial velocity.

We encountered difficulty with the "projectile gun" or whatever it is called because it disassembled itself every now and then, therefore the tightness of the spring in the gun varied, in turn, varying the force (and the initial velocity) in which the ball was released. This arose when we were measuring the height with the angle of inclination at 30 degrees. We had erratic data during this part, i.e., the distance fluctuated up and down (due to the varying force) where it was supposed to resemble a parabola with simply one peak.

We were very efficient as a group, finishing ahead of time and encountering little difficulty apart from the aforementioned problem. I was also more useful this lab meeting- I was responsible for recording and encoding the data for my new group. I also became less shy with my group mates, mainly because they were very friendly with me. The initial awkwardness I felt with them last meeting was gone, and I hope that when we begin writing the technical report, I hope that my awkwardness with them would be gone, too.

This meeting made me realize how demanding physics research is. It was very tedious to repeat the same steps over and over again, therefore experimentation could be regarded as a test of endurance- it shows how dedicated one is as a scientist.

Saturday, January 29, 2011

On Projectile Motion

January 28, 2011; 8:30-11:30; NIP R108

My friend, Mac, and I were late this meeting because we finished the technical paper on the determination of g which, to our surprise, was not really due this meeting. It was sort of a relief because this allowed us to do some revisions.

When we entered, an experiment was already on its way. It involved a pump that was set to a variable angle and a metal ball was placed on the receiving end. When the pump was released, the ball would be flung and the distance it traveled was measured using a sheet of carbon paper.

The experiment was a display of projectile motion, which is the superposition of x and y motion. This two dimensional motion could be split up into its x and y components since the two are independent of each other. There is no x-acceleration while g is the y-acceleration.

The range (the x-distance) is computed as
X=Vi*cosA*t, where A is the angle of inclination
while the height (the y-distance) is computed as
Y=Vi*sinA-0.5g*t^2, where A is the angle of inclination
Rearranging the terms in the first equation, we can find t and plug it into the second equation
The values that we know are X and A, we do not know Y and Vi. We have to perform another experiment to find the value of Y or Vi to completely describe the system.

I was unfortunately separated from my group and was put into another. I really felt uncomfortable with my new group mates because I didn't know them.To add to that, I was not in my optimal setting because I didn't sleep that well the night before. Thereby, I wasn't really functioning that well and just became a pawn for them. I hope that I would be reunited with my old group the next meeting.

I realized this meeting that it is very difficult for me to work with people I barely know.

Thursday, January 27, 2011

On Technical Paper Writing

January 21, 2011; 8:30-11:30; NIP R108

Technical paper writing is one thing a good physicist must be adept at doing. For one to publish his findings, he must be able to communicate his ideas properly by following the recommended format set by the scientific community. It is important that I, as an aspiring physicist, to become an excellent technical paper writer.

Last meeting, we performed an experiment to find the value of g (~9.8 m/s^2) by using the air track set-up. We were tasked to write a technical paper that documented our findings.

We were taught the different elements of a technical paper (title, abstract, contents, nomenclature, chapters (composed of introduction, review of related literature, methodology, results, analysis, conclusion and recommendation), references and appendices). Sir Pacho also introduced us to the SPP (Samahang Pisika ng Pilipinas).

Everything this meeting was very reminiscent of high school science. In my HS, we were required to submit a technical paper once a year- each for integrated science, biology, chemistry and physics, and we were also given general guidelines to follow as to practice uniformity. It was something I admittedly dreaded doing, mainly because writing that kind of paper was very monotonous- I prefer creative writing. But still, I know that it is a MUST that I learn to appreciate it to become an awesome physicist.

Sunday, January 16, 2011

On Air Tracks and Experimentation

January 14, 2011; 8:30-11:30; NIP R108

This meeting's goal was basically to gather experimental data from an air track (which is virtually frictionless) set-up wherein a cart was pushed (with constant force- using a retractable pen) a variable distance (from 5 m to 45 inches close to the other end), taking note of how long it would take to complete its travel. The angle of the air track was also another manipulated variable (which was done by stacking books one on top of the other).

We were quite late this meeting because we rushed the lab report for the activity prior to this meeting. When we entered the room, our classmates were already gathered around the air track doing the experiment. I was assigned to record the time it took for the cart to reach the other end for a while but I was unable to try actually pushing the cart.

From raw experimental data, it became evident that the farther the distance from one end, the longer it took for the object to reach the other end. Applying a constant force in a frictionless surface entails that the acceleration of the object applied with the force is constant. Its velocity would increase in x increments per unit second. It was also evident that increasing the angle's measure would make it quicker for the object to reach the other end (due to the acceleration due to gravity).

The lab meeting was quite fast since the activity wasn't really that demanding. I realized this lab meeting that I knew only a handful of my classmates personally, and that I should be more sociable as to be able to enjoy the lab meetings in its entirety.