物理

一般人從小就知道如果要判斷西瓜有無成熟，只要用手輕拍瓜皮，利用聲音的特性就可以知道西瓜是否成熟，此技術看起來容易，卻需有多年經驗之西瓜商始可為之。本研究利用拍擊西瓜所造成之聲音進行非破壞性音波檢測，來探討西瓜之成熟度。換言之，本研究希望在依照西瓜商拍擊的習慣下，從客觀的科學角度，探討存在於西瓜商手上「聽音辨瓜」的奧秘。由研究結果得知，西瓜的拍聲在頻譜中可分為三個頻區，即西瓜殼所造成的高頻區，水及含水量高的果肉所形成的中頻區，及由空洞及含水量低的果肉所造成的低頻區，而西瓜商就是藉由這三種音頻所表現出的綜合效果進行判斷。The method, tapping the watermelon rind and listening to the sound, has been often used to judge whether the watermelon is mature or not. Although it is not difficult to tap the rind of a watermelon, it is not so easy to have a correct judgment of the maturity just from the sound you heard, unless you are an experienced watermelon farmer. In order to investigate the secret that the farmers have, this research detects and analyzes the sound of tapping watermelons in an objectively scientific way. According to the experimental results, the sound could be approximately partitioned into three regions in the frequency spectrum, denoted as high-frequency, mid-frequency, and low-frequency regions. The high-frequency region and mid-frequency region are resulted from the hard solid rind and the juicy flesh of a watermelon, respectively. As for the low-frequency region, it comes from the vacant holes or flesh with little amount of water. Based on the experiment, it can be concluded that the maturity of a watermelon can be correctly judged from the combination of these three frequency regions, just like the farmer’s method.

本實驗改良菲左測定光速之實驗，將原本的光路以光纖取代，並將原本的光源改為紅外光。做了上述的改良以後，可將實驗的空間及時間縮小。實驗中輸入固定頻率的紅外光載送週期性的訊號經光纖傳輸後，利用示波器觀察訊號的延遲時間，以此實驗技巧可精密計算出光速。在輸入訊號為0.1~5MHz時，光在光纖的平均速率為2.09×108 (m/s)。換算真空中光速c＝折射率n(1.467)×光纖中速率v(2.09×108m/s)＝3.03×108 (m/s)，平均百分誤差0.43%，平均誤差為0.13×108 m/s，準確度為99.57%。 若取最佳輸入頻率2~3MHz所得到之數值，光在光纖的平均速率為2.05×108 (m/s)。換算真空中光速c(3.00×108 m/s)＝折射率n(1.467)×光纖中速率v(2.05×108 m/s)，平均百分誤差為0.33%，平均誤差為0.01×108 m/s，準確度為99.67%。 A method using optical fiber is described for measuring the velocity of light . Measuring the velocity of light usually needs a long distance and in a brief time. These experiments use optical fiber and TOSA and ROSA

A polysiloxane elastomeric lens was formed by mixing a silicone elastomeric base and silicone elastomer curing agent. It was molded from a +100 glass lens attached to a milled Plexiglas mold. The changing focal length as a result of the application of different degrees and ways of applying strain was observed with the help of a diverging laser beam and 28 and 30- diopter lenses. The shortening of the focal length as a function of applied strain using weights was observed for two treatments namely low weight and high weight. The focal lengths were measured using a vernier caliper and an adjustable white board on which the laser beam was reflected. Data for the experiment involving weights showed that there is a general decrease in the length of the foci of the elastomeric lenses as more weights were added to the set-up. This can be attributed to the increase in curvature of the lenses as more weights were added. Data for the experiment involving spring balances showed that there is a general increase in the length of the foci of the elastomeric lenses as the spring balances are pulled harder. This can be attributed to the flattening or decrease in curvature of the lenses as the spring balances are pulled harder. A stretchable lens can be used to replace intraocular lenses in cataract extraction. By changing the focal length, the lens can work for a wide range of distances, and therefore serve as the definite solution to the development of cataracts and other conditions that affect visual activity.

本研究欲探討垂直水柱遇障礙物成節的形成機制。以數位照相機、光電計時器等進行觀測。 實驗結果如下： （一）因往返水柱波速不同，而且節無波腹大幅振動現象，故節不是駐波現象。 （二）細針插入水柱表面時，當針上方超過某長度後，針下方產生Ｖ字形震波。但不論針相對水柱的速度是否超過波速，針上方都有節，故不是震波所產生的現象。 （三）根據水波槽模擬實驗，不論木條是否超過波速，木條前方均產生波紋。木條前方的水受到木條推動，往前方加速，因此顯現出波紋了。 我們認為，在水柱中所看到的節，不是震波或駐波，而是相對於木條往前傳遞的波。波源是撞擊物，改變了水柱表面的壓力，而成為波源，水柱的水因受撞擊，某個範圍內流速會小於波速，使得撞擊物前方存在波紋。This experiment uses digital camera and photoelectric timer to discuss the mechanism of causing spouts to form nodes on its surface. Because the downward wave velocity of the spout is different from that upwardand there are no significant vibrations of antinodes, standing waves are not the mechanism of causing nodes. In the experiment of inserting a needle into the spout, we found out that while the needle was inserted above a certain length of the spout, v shaped bow waves emerged. However, no matter the velocity of the needle related to the spout is over the wave velocity, there are always nodes above the needle. Therefore, bow waves are not the mechanism of causing nodes. According to the ripple tank simulating experiment, no matter whether the speed of the wooden stick is faster than the wave velocity or not, there are always waves forming in front of the wooden stick. The wooden stick pushes water in front of it and causes the water to accelerate forward. Therefore, waves appear. We think that the nodes we see on spouts are neither standing waves nor bow waves. The nodes are rather caused by the relatively moving wooden stick. The object, which impacted the spout (wooden stick), changed the pressure of the spout’s surface and became the source of wave. Because of the impact, the velocity of the water current of a certain area became slower than the wave velocity and causes nodes forming on the surface of the spout.

本研究主題是要探討以電解質作為電介質之電容器的放電情況及電容值。作者在電容器的兩極板中，灌入電解質溶液，作為電介質，發現確實能使電容值大增。作者再以不同電解質和外加磁場為變因，作出以下研究,以深入了解電容和電解質溶液的關係。The main idea of this topic is to explore the amount of capacitance with electrolyte as dielectrics. The authors poured electrolyte solutions into the polar plate of capacitor and found the amount of capacitance increased. Then the authors used the different kinds of electrolyte and added magnetic field as changing factors. Authors performed the following research to deeply find out the correlations between capacitance and electrolyte solutions.

A cylinder rolling on an inclined plane and a sphere on grooved tracks are discussed in details.Using elementary mechanics, the formulas are derived for the time interval (t) and the final speed (vas a function of release height (h). (1) A cylinder is rolling down an inclined plane. The speed and time of the center of mass ofthe cylinder which changed with position (x) are recorded by a motion sensor. We can get theplots of v vs. √x and t vs. √ x, and find that the acceleration of the center of mass of thecylinder is constant, whether the cylinder is in rolling or a combination of rolling and slipping. (2) A sphere is rolling down an inclined grooved track. The final speed at the bottom of thetrack can be calculated from the physics of projection motion after the sphere leaves the track to thefloor. The time t for the sphere starting from rest to the bottom can be recorded by using photogate detectors. From the v-√h and t-1/√h graphs, μs between the sphere and track can be obtained. (3) When a sphere is released from the vertical height h of a cycloidal slide, the time tof pure rolling is the same independent of release position. But, when the sphere moves at a combination of rolling and slipping, the time t' will be different from t. We measure t and t' with photogate detectors and get the plot of t vs. h. The value ofμs can be calculated from the t - h graph. 圓柱或鋼珠從斜面或有槽曲面形成的軌道上滾下時，利用基本力學，可推導出時間 (t) 、速率 (v) 隨高度改變的函數關係。 (1) 利用運動感應器記錄圓柱由斜面上滾下時，圓柱質量中心的速度及運動時間隨位置 (x) 的變化，可繪出 v 對√ x 及 t 對 √x關係圖，由v－√x 及 t－√ x圖可知不論圓柱純滾動或滾動兼滑動，其質心均等加速度運動。 (2) 鋼珠由有槽斜板滾下時，到達底端的速率可由從底端至地面的拋體運動算出，而其時間t則可利用光電計時器直接記錄，利用 v－√h 圖及 t－1/√ h 圖可求出鋼珠和軌道的靜摩擦係數 μs。 (3) 鋼珠從旋輪線上方純滾動至底端時，所經歷的時間 (t) 和釋放高度無關，但是當鋼珠滾動兼滑動時，所經歷時間 t' 會改變，利用光電計時器量出 t 及 t'並作圖，利用 t－h 圖可出 μs。

在本次實驗中，我們發現在不同厚度的磁流體薄膜中，會因本身磁性粒子結合，而呈現不同的影像圖形。隨著薄膜厚度增加，其磁性粒子會由鏈狀排列成塊狀叢集，可是一旦外加磁場後，又要全部轉向磁力線方向集結。另一個發現是將磁流體薄膜放在一個不均勻的磁場梯度中，則樣品內的磁流體粒子，不僅會隨著磁力線的方向排列移動，更會出現磁流波紋，其行進路徑是沿著垂直於磁力線的方向，向磁力線密集處移動。我們亦發現在不同的薄膜厚度及不同外加磁場下，其”磁流波紋”的波速亦會隨之改變。一般而言，樣品的厚度愈厚，或外加磁場愈大，其”磁流波紋”的波速愈快，反之則愈慢。最後，我們列出了一些磁流波紋的應用，相信是精采可期！In this experiment, we find that in different thickness of magnetic fluid different images will appear, because of the connection of magnetic particles. With the increasing of thickness the magnetic particles will change its shape from chains to blocks. But when we add external magnetic field, they will get in line one by one to the direction of magnetic line of force. We also find that we put the magnetic fluid film in the uneven magnetic gradient, the magnetic particle in the sample not only follow the direction of magnetic line of force but also show the “magnetic wave”. Its move path is perpendicular to the direction of magnetic line of force. In the different film thickness of magnetic field, the wave velocity of the “magnetic wave” will change. In generally, the thicker the sample is, or the larger the magnetic field is, the faster the wave velocity of magnetic wave is and adverse is true. At last, we list the applications of “magnetic wave”, we believe they are marvelous!

「風笛」是台灣原住民鄒族的信號用具及祈雨法器，由一條繩子綁一支竹片構成。轉動風笛時，竹片會繞繩子自轉並拍打空氣而發出聲音，並有上下飛舞的現象。 \r 風笛產生聲音的原因，為竹片拍打空氣而造成的渦流共振現象；又由於繩子扭力大小及方向改變，使風笛的音調忽高忽低、響度忽大忽小、且竹片會在兩個平面上公轉，而有週期性變化。 \r 施力使風笛公轉轉速加快時，竹片自轉速率也變快，使其音調愈高、響度愈大；而繩愈短、愈粗時，竹片的公轉週期將愈短。

本研究從大自然中之「蓮花效應」引發學習興趣與研究動機，在蒐集相關資訊與文獻後，發現疏水功能不只是防水，還關係著日常生活品質之許多材料特性，包括防水、撥水、防潮、防銹、防蝕、抗菌防污、自清潔…等。而影響固體表面疏水性之兩大特性，包括物理之表面粗糙度與化學之超低表面能，本研究針對物理之表面粗糙度與疏水性之關係做探討，以相同之化學特性來比較不同號數之工業用砂紙之疏水行為，並就廣泛被引用之兩種模擬表面粗糙度與疏水性關係之模式：Wenzel and Cassie model，比較現有文獻對兩種模式之特性，選擇Cassie model 來進一步實驗驗證，以量測之平均接觸角 Θ 推算Cassie model 之表面粗糙係數Φ 值，並簡化不同砂紙顆粒模型為相同粒徑之球狀，以簡化之方程式來求得水珠與砂紙顆粒之實際接觸面積與球心夾角 θ，以提供高中學校能在經費與設備之限制下，仍能有效應用與印證Cassie model，獲得砂紙顆粒直徑與球心夾角 θ 自然對數值之關係。並就疏水性之生活應用，建立接觸角與 Φ 之關係曲線，驗證實驗之方程式，與延續過去之科展成果，以實驗成果提出可行性應用之建議。The interest and motivation of the present work was introduced from “lotus effect” in nature. After we collected related literature and information, we found that the function of the so-called “superhydrophobicity” behaves not only water repellency, but also a variety of real-life applications, including anti-fog, anti-corrosion, anti-bacteria, anti-fouling, self-cleaning, and so on. Pervious studies have pointed out that two criteria affecting the performance of hydrophobic surfaces are physical (roughness) and chemistry (surface tension) properties. This study focused on influence of physically surface roughness on hydrohyphobicity. Based on an identical surface chemistry, we employed different types of industrial sandpapers to mimic the lotus leaf, and investigated the relationship between roughness and hydrophobicity by using two famous models: Wenzel and Cassie models. Comparing with their basic assumptions to our study, we applied Cassie model to confirm our experimental results, in where one Cassie parameter (?) was proposed to simplify the Cassie equation. This superhydrophobic behavior can be well predicted by the Cassie model. This study continues previous achievement and offers some practical utilization according to our\r experimental results.

本實驗使用磁流變流體(Magnetorheological fluid, MRF)來估查其磁場作用下的光學性質。本實驗採用Lord公司的MRF-132LD磁流變流體加以稀釋到不同的重量濃度，並以氫氟酸蝕刻玻片產生不同的厚度。吾人觀察到濃度參數以及厚度參數均對MRF薄膜的光繞射產生影響。膜厚越薄，產生的繞射較明顯，而重量濃度較小的容易亦有較大的繞射角度。吾人亦移動上下兩玻片相對位置，施加剪力的作用，繞射現象也產生明顯的改變。\r The Magnetorheological fluid (MRF) is used to observe the optical properties under the vertical magnetic field , The MRF-132LD from Lord Company is used, The MRF is diluted to different weight ratio of particulate and carrier fluid . The different thicknesses of the MR thin film are also made with the diluted MRF. The concentration of the MRF and the thickness of the thin film are both found to have significant effects on the optical diffraction phenomenon. The optical diffraction is also found to be affected by the applied shear force to the thin film.