氣泡在黏滯性液體中的運動
本研究目的在探索不同大小之氣泡在不同黏滯性液體中運動情形。實驗結果發現大氣泡向上運動的速度較大，其下方會漸漸向內凹。並且觀察到氣泡間結合時的相互作用：氣泡在相同黏滯性膠水中上升時，若下方氣泡體積較大，其較快的速率會使距離縮短。此時小氣泡的下半向內凹，大氣泡的下半則向外呈現流線型尖端並且在接近小氣泡時速率增加，最後與小氣泡結合。若上方氣泡體積很小，與下方大氣泡的距離縮短至相互貼合，小氣泡會先停留在大氣泡的上半表面，再沿大氣泡表面下滑至大氣泡的下半才與大氣泡結合。This research traces the motions of bubble with different volume in viscid liquid. The experimental results show that the bigger bubble rises at faster speed. The shape of the small bubble is round. As the volume of the bubble increases, it turns hamburger-like. And if the bubble is big enough, its underside would be concaved. In viscid liquid, the speed of the bubble is not smooth but waved. The smaller the bubble is, the more the variation in speed is. The interaction of two bubbles is also studied. There are two types of the combination of two bubbles. While the big one closes to the small one, it is accelerated. The underside of the small one becomes concave. And the big one becomes streamline shape. If the difference in volume between two bubbles is significant, the small one slides along the surface of the big one, and goes into the concave beneath it, then combines with it.
酒杯發出之音符
When you draw a wet finger around the edge of a half filled wine glass, a sweet musical sound comes forth. The pitch of this sound is directly correlated to the amount of liquid in the glass- the higher the height of the liquid is, the lower the frequency is. It means that the shorter the air column in the glass is, the lower the frequency is. This phenomenon differs from the variance in pitch in a wind instrument. In a wind instrument such as a flute, the shorter the air column in its chamber is, the higher the resulting pitches are. In order to study the wine glass phenomenon, we used a piezoelectric crystal loudspeaker connected to an oscilloscope. We recorded the resulting data by using a digital video recorder to capture the images of the waveform of sound, and than analyzed the waveform by using the computer. Our conclusions are as follows: 1. The frequency of sound thus produced was the same whether we draw our finger around the rim, or we strike the glass rim. The higher the height of the liquid is, the lower the frequency is. But the frequencies vary when we strike the glass and when we blow on the edge. 2. When we used a glass without liquid in it, the frequency emitted when we drew our finger around the edge, this frequency varied inversely as the cube root of their weights. 3. In a glass with liquid, the emitted frequency did not have any correlation to the weight of the contents. By taking two identically filled glasses and placing in each a solid object of the same size but different weight, we were able to see that there was no change in the frequency emitted between the two glasses as long as the height of the liquid remained constant. 4. According to “The Flying Circus of Physics”, if we tap the side of a glass of beer, because of the air bubbles in the beer, the frequency emitted will be lower than that from a glass of pure water. This is according to the book, because the speed of sound is lower in air than in water, therefore the speed of sound in an air-water mixture would be lower than in pure water. The resonant frequencies of the mixture will also be lower. However, in our experiment, we discovered that\r when the glass contained air bubbles, the frequency emitted higher. Our explanation is that the sound emitted since the rim of the glass oscillated transversely, the frequency depends only on the retard of the rim and that the frequency is independent of the speed of sound. The intention of this research is to clarify the many misconceptions of this interesting phenomenon.以溼的手指在玻璃酒杯邊緣摩擦，會有悅耳的聲音，而且頻率會隨著內裝液體減少（空氣柱變長）而變高，這種變化與管樂器隨空氣柱的變長而音調變低不同，為了研究它的原因，我們利用壓電晶片喇叭連接到示波器上，並且利用數位錄影機錄下示波器上的訊號，再以電腦分析出瞬間的頻率，結果發現：一、摩玻璃杯與敲玻璃杯，杯所發出之頻率相同，都是所裝液體愈多發出之頻率愈低。但敲玻璃管與吹玻璃管所發出之頻率不同。二、不裝液體之高腳杯，摩擦時所發出之頻率與重量之立方根成反比。（與鐘相同）\r 三、裝液體之高腳杯發出之頻率，不再與總重量有關，而是與液體之高度有關，保持液體高度不變，即使在杯子中央加入不同重量之固體，杯子振動頻率還是不變。若改裝不同密度之液體，則密度愈大頻率愈低。四、在“The Flying Circus of Physics”書中提到輕敲裝有啤酒之杯時，會因杯中含有氣泡而聽到較低之音調，書中解釋是”空氣中之音速低於水中之音速，混有空氣之水中音速變低，其共振頻率也會降低。”但我們的實驗結果是有氣泡時頻率反而高。我們的解釋是杯子所發出之聲音是由於杯面之振動也就是杯壁的橫向振盪，振盪頻率與液體對杯壁之阻尼有關，但與液中聲速無關，密度愈大之液體阻尼愈大。有氣泡時接觸杯壁之液體變少，阻尼較少所以頻率高。希望本研究能使大多數人對這有趣之現象不再有誤解。
推著離子跑
在本次實驗中，我們發現溶液中的帶電離子，會因為離子團的熱運動，和電偶極的庫倫吸引力(electric dipole)的交互作用下，使得電解質溶液的I-V curve(電流-電壓 曲線)，具有類似磁滯曲線(Hysteresis curve)的效果，同時我們運用光學干涉的原理，證實此時在電場作用下，離子團會互相順著電場方向作條列鍵結，而加熱實驗也證實，熱運動會使溶液的I-V curve(電流-電壓 曲線)變的不一樣。另一方面，我們也發現，在給予電解質溶液一外加的衝擊電壓時，該溶液的電荷分布，?會因為彼此的互相擠壓以及自由擴散的作用下，而形成一震盪分布，其所顯現出來的，則是電壓的震盪變化。最後由於震盪波紋的變化，在起始時與中段之後有著明顯差異，我們對此變化提出看法和證實，相信內容是精采可期的！ In this experiment, with the interaction of the heating action of ionic atmosphere and electric dipole, we find that ionic in the liquor makes the I-V curve in the electrolyte liquor show up with the effect similar to Hysteresis curve. Meanwhile, we practice the principle of interference to prove that at this moment, under the influence of electric field, ionic atmosphere will connect to each other in line following the direction of the electric field. It is also proven that in the heating experiment, heating action will make I-V curve in the liquor different.On the other hand, we also find with extra electric impact, the charge distribution of the liquor will form a oscillation, that is, the changes of the voltage oscillation under the inter-collision and the free spread. We offer our viewpoints and proofs about the obvious changes of oscillation wave in their beginning stage and after their middle stage. We believe that the marvelous content is surely worth of your expectation.
昆蟲模擬-雙振翅翼
本研究的目的在於探討蜻蜓兩對翅膀在不同的相位差之下對升力有什麼影響。在觀察蜻蜓及察閱相關網站、研究後發現蜻蜓前後翅的相為差有相差0.5 週期、相差0.25 週期、同週期三種不同振翅方式。在界定欲實驗的種類和評估現有的能力及資源後，決定研究加上相差為0.125 週期的四種振翅方式，於無風條件、相同的振翅頻率下進行實驗，測量其升力的變化週期。測量結果參照前人的文獻後發現，0.5週期產生的升力雖最小，但最平穩，所以為蜻蜓最常用的飛行方式。而0.25 週期升力會疊加，往下的力被抵銷，故為向上加速時使用。 ;The purpose of this study is to investigate the phase-shift between the front-pair and rear-pair wings on the maximum lift of a dragonfly. As observing the flight of a dragonfly and the literature survey from web sides, it has been observed that the general phase-shift modes of the dragonfly are in-phase-shift, 1/2 period and 1/4 period. It has been decided to include a 1/8 period phase-shift mode into the known three modes under the no wind condition with a fixed flapping frequency, the cyclic lift force of the dragonfly wing model has been measured. When it is flapping, we put the model on an electronic scale for measuring the weight of the model. After that we minus the original weight of the model, knowing the increasing or decreasing weight and the extra weight is the lift force. The results show that 1/2 period phase-shift mode produces the least lift force; however, it is the most stable flight, and is being adopted by the dragonfly for level flight. The in-phase-shift mode can produce more lift force on the flapping processes. The 1/4 period phase-shift mode produce the most acceleration, being adopted by the dragonfly for the climb flight.
創新儀器測量光的繞射與干涉之強度分佈
Light diffraction and interference are two of most basic experiments, but they’re the most powerful evident of wave properties of light. Due to the lack of high-quality and fairly accurate equipment, these important experiments are limited to the simple demonstration of the phenomena. Especially, the spatial intensity variations of diffraction and interference patterns are, however, completely not drawn to scale. In order to precisely measure the diffraction and interference patterns intensity, we consult lots of reference, search for suitable materials and reuse waste old and useless laser printers. Finally, overcoming disadvantages of time consumption and poor spatial resolution, we develop two accurate, practical and delicate methods. We use optical power control circuit created on our own to steady the brightness emitting of laser diode. Then the high linear photoelectric detector is stored on XYZ axis micro movement control platform. Next high degree of reflection rotating polygon mirror employing optical lever is collocated with low vibration blushless motor. Thus, a self-scanning intensity pattern plotter is accomplished. At the same time, it overcome difficulties like time wasting and low reliability during doing these kind of optical experiments. In this article these two dependable and worth popularizing measurements of light diffraction and interference is going to be introduced. 光的繞射與干涉實驗是光學中最基本的實驗之一，也是證明光的波動性質之最主要的依據。在一般的高中物理實驗室中受限於器材的等級與精度，只能對光的繞射與干涉做近似定性的實驗，尤其是繞射、干涉圖形上的光能量分佈，完全無法以現有的器材做精準的測量。 在這一年的專題研究中，我們小組針對測量光的繞射、干涉能量分佈為目標，參閱許多相關文獻，四處尋找適用的材料及零件，發揮廢物利用的精神，克服萬難，發展出兩種精巧、實用又準確的測量方法，我們以自行發展的光功率控制電路使雷射二極體的光度穩定，並且以高線性度的光感測元件裝載在自行設計的X.Y.Z微動機台上，同時利用光槓桿原理所構成的高反射度的旋轉六面鏡，配合低震動的無刷馬達，完成了一套能自動掃瞄繞射能量分佈曲線的測試儀，經實際使用相當地穩定可靠，可以快速而精確地獲得大量的實驗數據，比對這些數據不僅能驗證繞射理論，並能更深入地延伸理論的探討。