In the labs

The academic year at Imperial College for physics students usually begins with laboratories. This is a bit unpleasant part of our studies, because it is time-consuming, exhausting, and the resulting mark does not count very much towards your degree. However, it is the honour of each student to work hard in the labs, as it is a direct sign of his or her skills and knowledge applied in practice.

The motto of labs at our university is to provide students with minimal instructions on how to perform an experiment. This means that a student is instructed to set up all measuring devices and decide how to measure experimental data based on theoretical knowledge only. Perhaps it is good to use the method of trial and error sometimes, when no lab demonstrator, who is considered to be a qualified laboratory technician, is present. Lab demonstrators pass by students and give them questions on theory and method of a conducted experiment so that they can assess the student’s performance in this challenging work environment. Sometimes, however, the demonstrators have an empathy with students and give us some guidance how to conduct an experiment, or reveal how we should analyze measured data, i.e. which part of data will be of some physical significance in an attempt to draw conclusions. Physics labs are mostly a test of the students’ patience. Students are supposed to work in pairs, meaning each student has to find a lab partner. The ability to cooperate with your lab partner is of a great importance because it is assessed by demonstrators. In the end, it would be without a lab partner impossible to conduct some experiments, when it is required to get hundreds of measurements in a short time. It is also necessary to keep a written lab book and analyze measured data during lab sessions. The analysis is almost impossible without having a discussion with your demonstrator. From my point of view, each student will eventually get into a situation, where he or she tries to handle several tasks simultaneously and this is not always easy. I encountered an incredibly challenging situation when I tried to measure together with my lab partner temperature waves. The aim was to determine the diffusivity coefficient of the Poly-Tetra-Fluoro-Ethylene cylinder. It was quite easy to set up the apparatus which consisted of pieces of ice, a heater, a flask, a beaker and the cylinder. The experiment’s method appeared to be perhaps even simpler. We were supposed to place the cylinder into a hot and cold water in the flask and beaker alternately to make a periodic temperature wave, which was measured by a digital thermometer placed inside the cylinder. However, only after a few attempts to measure the temperature wave, we realized that the seemingly simple task is complicated and a remaining time flew. I stirred the beaker which contained ice eagerly so the water substance inside could reach the optimum melting temperature. A moment of inattention often caused that the cylinder was a little longer in cold or hot water. Consequently, a sinusoidal wave changed its appearance and it looked like a wave with a shape of stairs to our laboratories. As ubiquitous and all-knowing lab demonstrators told us, patience is the key to success.  One important concern of lab demonstrators was our safety because, during the process of mixing, water in the beaker sometimes splashed directly on the electrical components of our heaters. Fortunately, these accidents led to a power failure only. The effort to measure a temperature wave was interrupted for all present students in these situations. First of all, the goal was to measure a temperature wave and the required wave’s period was three minutes. Work on this task usually took about an hour and it required placing the cylinder into the cold and hot water for 90 seconds alternately. Many things could go wrong in the task, including the failure of the digital thermometer. However, a real challenge was to measure the temperature wave for a longer period. I think I eventually managed to measure together with my lab partner the temperature wave which had a period of seven minutes. Nevertheless, including unsuccessful attempts, it took a lot of hours. With a feeling of satisfaction, we completed the measurements. However, this feeling did not last for a long time, because we found that analyzing the measured data is perhaps even more difficult than producing a temperature wave. More specifically, we had to use Fourier analysis method and the Bessel functions. Time for this task was also limited as we had 48 hours only to write a lab report and we also had to summarize findings from another big experiment in the lab report simultaneously on the propagation of waves in an electrical circuit. I submitted this "double" lab report after a sleepless night. I was exhausted but had a good feeling of a researcher, and the mark awarded to this report lifted my spirit in the end. Hence, in conclusion, I can say that patience pays off. I am looking forward to more adventures that are waiting on me in the third-year labs.

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