最近1 hour 線上瀏覽紀錄.216
  1. 22:39:IP=110.28.106.179:-1 from Tucheng(tw)1:琉璃光電磁波
  2. 22:39:IP=110.50.165.36:-1 from Taipei(tw)1:關於乾冰昇華的白煙
  3. 22:39:IP=66.249.69.181:-1 from Mountain View(us)1:燈泡燈絲不遵守歐姆定律?
  4. 22:39:IP=207.46.13.231:-1 from REDMOND(us)1:撕膠帶要有技巧?
  5. 22:38:IP=39.12.165.118:-1 from Taipei(tw)1:何者是吸熱反應
  6. 22:38:IP=66.249.82.116:-1 from Mountain View(us)1:頭快想破了(吳瀲竹)
  7. 22:38:IP=1.160.74.246:-1 from (tw)1:雷射光不會散開
  8. 22:38:IP=66.249.69.175:-1 from Mountain View(us)1:環型駐波振盪和電子軌道運動
  9. 22:38:IP=223.141.26.231:-1 from Tucheng(tw)2:夜市套圈圈遊戲的精心設計∼
  10. 22:38:IP=66.249.75.191:-1 from Mountain View(us)1:Helmholtz coil 均勻磁場/鏡像磁場: 早期磁控電漿裝置
  11. 22:37:IP=66.249.69.177:-1 from Mountain View(us)1:飛機與變化球
  12. 22:37:IP=106.1.229.179:-1 from Tucheng(tw)1:面鏡?透鏡?
  13. 22:37:IP=180.217.157.150:-1 from Tucheng(tw)1:無限深方形阱
  14. 22:37:IP=157.55.39.253:-1 from REDMOND(us)1:為何坐飛機時可以看到一整片\"平坦\"的雲?
  15. 22:37:IP=66.249.69.173:-1 from Mountain View(us)1:[材力]扭矩-附圖 只問觀念附自己思考過程
  16. 22:37:IP=223.137.67.144:-1 from Keelung(tw)2:轉動慣量之實驗
  17. 22:37:IP=42.73.168.100:-1 from Tucheng(tw)1:[請益] 音速與溫度的關係?
  18. 22:36:IP=59.127.240.77:-1 from Taipei(tw)1:托里切利實驗
  19. 22:36:IP=66.249.82.120:-1 from Mountain View(us)1:關於橢圓軌道的平均半徑
  20. 22:36:IP=66.249.82.118:-1 from Mountain View(us)1:何謂磁量?
  21. 22:36:IP=39.12.0.68:-1 from Taipei(tw)1:接觸起電
  22. 22:35:IP=218.173.50.8:-1 from Taipei(tw)1:有關Laplace\'s equation的問題
  23. 22:35:IP=49.216.62.156:-1 from Taipei(tw)1:失重狀態 代表 只受重力作用?
  24. 22:34:IP=66.249.81.247:-1 from Mountain View(us)1:1埃約為一原子的大小,那麼光譜的4000埃是否就是原子核四千倍的距離呢?
  25. 22:34:IP=1.171.13.5:-1 from Taipei(tw)1:百分誤差的計算
  26. 22:34:IP=123.125.71.86:-1 from BEIJING(cn)1:天藍與海藍的原因(雷利與拉曼散射)
  27. 22:33:IP=180.204.145.117:-1 from Tucheng(tw)1:相位超前落後
  28. 22:33:IP=66.249.69.184:-1 from Mountain View(us)1:音樂廳設計問題
  29. 22:33:IP=140.114.6.163:-1 from Hsinchu(tw)1:請問為何銀色表面不是良好的輻射吸收及發射體?
  30. 22:33:IP=36.226.193.159:-1 from Taipei(tw)1:金字塔能
  31. 22:33:IP=122.117.26.148:-1 from Taipei(tw)1:等角加速度(單位的問題)
  32. 22:33:IP=101.12.61.204:-1 from Tucheng(tw)2:平行板電場公式
  33. 22:32:IP=59.115.70.181:-1 from Taipei(tw)1:請問折射率如何計算?
  34. 22:32:IP=112.105.16.226:-1 from Tucheng(tw)1:線上LATEX編輯器
  35. 22:32:IP=223.138.221.202:-1 from Tucheng(tw)1:卡車入庫的問題
  36. 22:32:IP=114.44.181.148:-1 from Taipei(tw)1:關於電磁鐵磁導率的疑問
  37. 22:31:IP=114.38.56.84:-1 from Taipei(tw)1:發電廠交流電的傳輸
  38. 22:31:IP=223.141.183.40:-1 from Tucheng(tw)1:虛光子的物理意義
  39. 22:31:IP=49.216.69.28:-1 from Tucheng(tw)1:哈伯常數估計宇宙年齡
  40. 22:30:IP=122.254.44.49:-1 from Kaohsiung(tw)1:單細胞生物是否有神經
  41. 22:30:IP=180.217.197.140:-1 from Tucheng(tw)1:馬達220V的接線,用110V的電源
  42. 22:30:IP=223.141.25.57:-1 from Nantou(tw)2:環擺\
  43. 22:30:IP=118.165.159.219:-1 from Taipei(tw)1:黏滯係數 實驗結果 的 疑問(同主題)
  44. 22:30:IP=111.83.116.148:-1 from Taipei(tw)1:電擊棒的原理?
  45. 22:29:IP=111.241.44.163:-1 from Taipei(tw)1:眼睛看到的為什麼不是倒立影像?
  46. 22:29:IP=39.10.192.103:-1 from Taipei(tw)1:<棒球>球質輕重?
  47. 22:29:IP=220.181.108.185:-1 from BEIJING(cn)1:電力公司的地線有何用 , 為何會與插座的中線連接?
  48. 22:29:IP=180.204.193.5:-1 from Tucheng(tw)1:變壓器二次側一定要接地嗎
  49. 22:28:IP=49.217.16.51:-1 from Tucheng(tw)1:电流不是电子的移动
  50. 22:28:IP=66.249.75.163:-1 from Mountain View(us)1:作功\的題目
  51. 22:28:IP=114.45.163.188:-1 from Taipei(tw)1:石墨為什麼可以導電啊
  52. 22:28:IP=1.169.64.138:-1 from Tucheng(tw)1:合金
  53. 22:27:IP=111.252.203.188:-1 from (tw)1:水100度和沸騰的關係
  54. 22:26:IP=110.50.169.49:-1 from Taipei(tw)1:介質與波速還是波長有關..?
  55. 22:26:IP=101.12.3.28:-1 from Tucheng(tw)1:膨脹功\的迷思
  56. 22:26:IP=1.163.101.253:-1 from Tucheng(tw)1:並聯的電器也會互相影響?
  57. 22:26:IP=1.175.227.126:-1 from Taipei(tw)1:有關摩擦力的一些問題
  58. 22:26:IP=36.238.89.154:-1 from Taipei(tw)1:Hund\'s rules (洪德定則)涵義?
  59. 22:25:IP=140.134.217.12:-1 from Taichung(tw)1:雙狹縫實驗中為何沒有個別討論兩個狹縫的單狹縫繞射
  60. 22:25:IP=101.15.130.156:-1 from Tucheng(tw)1:推繩波波速時,為何行進波兩端張力大小相等?
  61. 22:25:IP=111.242.4.23:-1 from (tw)1:橢圓形的地球
  62. 22:25:IP=211.75.47.211:-1 from Tucheng(tw)1:電線為什麼要分\"單心線\"或\"絞線\"?
  63. 22:24:IP=118.170.85.42:-1 from Taipei(tw)1:9V電池驅動LED燈
  64. 22:24:IP=114.34.211.215:-1 from Taoy羹an(tw)2:邏輯:P則Q 與-Q則-P
  65. 22:24:IP=61.216.18.11:-1 from Taipei(tw)1:雞蛋從高處掉落不破(陳立輝)
  66. 22:24:IP=49.216.55.187:-1 from Tucheng(tw)1:伽利略溫度計定理
  67. 22:24:IP=114.32.208.217:-1 from Taipei(tw)1:蒸氣壓與沸點
  68. 22:24:IP=123.125.71.114:-1 from BEIJING(cn)1:請問慣性作用
  69. 22:24:IP=36.233.143.18:-1 from Tucheng(tw)1:中間抽頭的意義
  70. 22:23:IP=123.240.102.113:-1 from Taichung(tw)1:科氏力4:科氏力的簡介
  71. 22:23:IP=220.137.216.190:-1 from Taipei(tw)1:變分法筆記[一]
  72. 22:23:IP=140.124.249.125:-1 from Taipei(tw)1:濕度的定義是什麼?
  73. 22:23:IP=220.134.40.238:-1 from Taipei(tw)1:氫原子光譜實驗
  74. 22:22:IP=111.83.224.102:-1 from Tucheng(tw)2:電荷的疑問
  75. 22:22:IP=42.72.9.195:-1 from Tucheng(tw)1:波長與距離
  76. 22:22:IP=207.46.13.235:-1 from REDMOND(us)1:光的二象性
  77. 22:22:IP=207.46.13.239:-1 from REDMOND(us)1:有關電風扇的問題
  78. 22:22:IP=123.193.217.177:-1 from Taipei(tw)1:質量、質量數及核融合?
  79. 22:22:IP=36.236.193.197:-1 from Taipei(tw)1:u型管的壓力問題
  80. 22:22:IP=111.242.11.149:-1 from (tw)1:有關酯化反應
  81. 22:22:IP=180.217.233.245:-1 from Tucheng(tw)1:關於線積分保守場F證明
  82. 22:21:IP=1.162.148.174:-1 from Tucheng(tw)2:1/2 mv^2
  83. 22:21:IP=124.218.134.243:-1 from Taipei(tw)1:如何測量摩擦係數呢
  84. 22:21:IP=14.198.188.6:-1 from Central District(hk)2:紙飛機的流體
  85. 22:20:IP=223.138.103.35:-1 from Tucheng(tw)1:一公斤的棉花和一公斤的鋼鐵
  86. 22:20:IP=111.250.21.83:-1 from (tw)1:關於作功\的定義
  87. 22:19:IP=223.136.237.108:-1 from Tucheng(tw)1:delta函數與step函數
  88. 22:19:IP=123.125.71.43:-1 from BEIJING(cn)1:正向力?(Pan)
  89. 22:19:IP=140.113.122.229:-1 from Hsinchu(tw)1:雷射模態??
  90. 22:18:IP=1.175.232.173:-1 from Taipei(tw)1:電流會生磁的疑問
  91. 22:18:IP=140.116.120.135:-1 from Tainan(tw)1:關於陀螺
  92. 22:18:IP=36.233.71.149:-1 from Taipei(tw)1:為什麼北極沒有企鵝?
  93. 22:18:IP=140.117.184.94:-1 from Kaohsiung(tw)1:靜電感應與接觸起電
  94. 22:18:IP=61.224.142.99:-1 from Tucheng(tw)1:頻率不變
  95. 22:18:IP=219.71.221.55:-1 from Taipei(tw)1:單相2線220V電表量測110/220V準確度問題
  96. 22:17:IP=101.12.17.63:-1 from Tucheng(tw)1:電量的定義
  97. 22:17:IP=114.40.175.146:-1 from Taipei(tw)1:如何修補電線絕緣皮破皮?
  98. 22:16:IP=1.175.237.219:-1 from Taipei(tw)1:若我從10公尺高自由落體?
  99. 22:16:IP=111.242.23.53:-1 from Tucheng(tw)1:咖啡和奶混合後...可否求混合物的比熱容量
  100. 22:16:IP=111.242.5.87:-1 from Taipei(tw)1:火花計數器的問題
  101. 22:16:IP=111.242.5.121:-1 from Taipei(tw)1:星芒的產生原理?
  102. 22:15:IP=111.83.251.9:-1 from Tucheng(tw)1:科氏力,東西向的問題,想了好久一直沒辦法解決?
  103. 22:15:IP=123.110.27.37:-1 from Taichung(tw)1:困擾很久的問題...冰的熔化
  104. 22:15:IP=111.71.50.24:-1 from Tucheng(tw)1:為什麼電位差會產生電流?
  105. 22:15:IP=220.181.108.122:-1 from BEIJING(cn)1:坐标算符与动量算符的对易式是多少?
  106. 22:14:IP=220.135.213.142:-1 from Taipei(tw)3:摩擦產生的靜電
  107. 22:14:IP=42.76.228.222:-1 from Tucheng(tw)1:SHM考慮彈簧質量
  108. 22:14:IP=180.217.76.29:-1 from Tucheng(tw)1:請問磁學中的B跟H場有何不同???
  109. 22:14:IP=60.198.45.30:-1 from Taipei(tw)1:推導Maxwell熱力學關係式
  110. 22:13:IP=66.249.69.183:-1 from Mountain View(us)1:近乎直立竿子在水平面上滑倒
  111. 22:13:IP=180.204.136.252:-1 from Tucheng(tw)2:警示燈光常使用 \"紅光\" 原因為何?
  112. 22:13:IP=101.12.102.103:-1 from Tucheng(tw)1:靜電力 和 重力 與距離平方成反比 是否\"必定\"如此??
  113. 22:13:IP=114.33.68.113:-1 from Taichung(tw)1:已知水頭水壓、高程、管截面積及所需流量,求減壓量
  114. 22:13:IP=27.52.33.123:-1 from Tucheng(tw)1:曲率半徑
  115. 22:12:IP=118.169.170.65:-1 from Taipei(tw)1:電磁波, E x B
  116. 22:12:IP=223.136.23.74:-1 from Tucheng(tw)1:超距力(mine)
  117. 22:12:IP=61.230.104.59:-1 from Taipei(tw)1:滑輪與細繩張力
  118. 22:11:IP=66.249.69.185:-1 from Mountain View(us)1:交流電 單相,三相與插頭的接地線(黃福坤)
  119. 22:10:IP=218.173.46.27:-1 from Taipei(tw)1:視覺暫留
  120. 22:10:IP=61.62.127.5:-1 from Pingtung(tw)1:什麼是官能基
  121. 22:10:IP=220.181.108.110:-1 from BEIJING(cn)1:奇想:輪盤形磁石再接上馬達
  122. 22:09:IP=111.250.179.126:-1 from Tucheng(tw)1:酸鹼中和,結晶
  123. 22:09:IP=42.73.6.57:-1 from Tucheng(tw)1:電路中的先知先覺/後知後覺與馬上辦中心
  124. 22:09:IP=140.114.125.22:-1 from Hsinchu(tw)1:介電常數問題
  125. 22:09:IP=111.71.14.161:-1 from Tucheng(tw)1:PV=nRT 理想氣體方程式
  126. 22:09:IP=223.136.140.246:-1 from Tucheng(tw)1:要如何準備奧林匹亞考試
  127. 22:09:IP=223.140.208.211:-1 from Tucheng(tw)1:磁場相斥,可以隔磁嗎?
  128. 22:08:IP=115.82.211.115:-1 from Taipei(tw)2:關於終端速度??
  129. 22:08:IP=223.140.109.177:-1 from Tucheng(tw)1:\"即溶\"奶粉或咖啡為何有\"即溶\"效果?
  130. 22:08:IP=123.0.42.212:-1 from Taipei(tw)1:玻璃杯的敲擊聲音
  131. 22:08:IP=220.134.139.250:-1 from Tucheng(tw)1:[請益] 防止「過度沸騰」的原理?
  132. 22:08:IP=14.198.64.95:-1 from Central District(hk)1:跟平面鏡有關
  133. 22:08:IP=219.69.98.245:-1 from Taipei(tw)1:一大卡的定義
  134. 22:08:IP=140.116.1.143:-1 from Tainan(tw)1:關於 g (克)及 gw(克重) 的分別(陳秉)
  135. 22:08:IP=101.15.216.80:-1 from Tucheng(tw)1:求 物奧書單
  136. 22:07:IP=114.41.219.5:-1 from Changhua(tw)1:摩擦力and接觸面積大小
  137. 22:07:IP=220.135.102.221:-1 from Taipei(tw)1:物體的散熱與熱傳導係數的關係
  138. 22:06:IP=118.167.153.232:-1 from Taipei(tw)1:有關車子的行進問題
  139. 22:06:IP=36.232.22.204:-1 from Taipei(tw)1:食鹽結晶的特殊X形花紋!
  140. 22:06:IP=220.181.108.157:-1 from BEIJING(cn)1:電磁感應的一個小問題
  141. 22:05:IP=123.194.189.4:-1 from Taipei(tw)1:氣體溶解度
  142. 22:04:IP=223.136.30.200:-1 from Tucheng(tw)1:滾動與摩擦力
  143. 22:04:IP=123.192.92.64:-1 from Taipei(tw)1:請問同相 相角 相位 相位差是啥東西
  144. 22:04:IP=111.242.33.108:-1 from Tucheng(tw)1:如何防止靜電
  145. 22:04:IP=114.137.160.151:-1 from Taipei(tw)1:請問有關E=hv的問題
  146. 22:03:IP=180.217.80.251:-1 from Tucheng(tw)1:鹽類與冰塊混和為何溫度會下降?
  147. 22:03:IP=114.34.215.86:-1 from Tucheng(tw)1:相變化時加熱為何只改變位能,不改變動能?
  148. 22:03:IP=39.10.196.149:-1 from Taipei(tw)1:日光燈只亮兩端?是為什麼呢?
  149. 22:03:IP=219.71.37.115:-1 from Taipei(tw)1:天秤測量質量
  150. 22:02:IP=220.137.209.34:-1 from Tucheng(tw)1:同質料、相同粗細但長短不同的彈簧彈性係數何者較大?
  151. 22:02:IP=1.169.108.202:-1 from Taipei(tw)1:替代能源--閃電的運用
  152. 22:02:IP=42.76.34.243:-1 from Tainan(tw)2:由三相220V電接出單相220V電造成馬達毀損
  153. 22:02:IP=223.138.115.243:-1 from Tucheng(tw)1:肥皂膜的厚度(Clarence)
  154. 22:01:IP=180.217.89.183:-1 from Tucheng(tw)1:靜力平衡的條件(觀念被混淆,極度混亂)
  155. 22:01:IP=59.120.251.134:-1 from Tucheng(tw)1:何謂熱容量?~急件!
  156. 22:00:IP=27.52.43.3:-1 from Tucheng(tw)2:助燃性的爭議?
  157. 22:00:IP=114.35.80.40:-1 from Taipei(tw)1:Circuitlab線上電路模擬器
  158. 22:00:IP=111.255.17.223:-1 from Tainan(tw)1:磁鐵的束縛電流
  159. 22:00:IP=36.230.122.211:-1 from Taipei(tw)1:電阻為何會因溫度增加而增加?
  160. 21:59:IP=61.231.54.235:-1 from Taipei(tw)1:光粒子論的光子折射問題?
  161. 21:59:IP=42.73.179.239:-1 from Tucheng(tw)1:平行板電容的疑惑
  162. 21:58:IP=36.237.214.217:-1 from Taipei(tw)1:電容的原理
  163. 21:58:IP=1.200.192.86:-1 from Taipei(tw)1:黑體輻射的問題
  164. 21:58:IP=140.115.225.98:-1 from Taoy羹an(tw)1:誤差值的計算
  165. 21:58:IP=118.170.189.88:-1 from Tucheng(tw)1:電位差如何產生?
  166. 21:58:IP=39.12.138.125:-1 from Taipei(tw)1:為什麼氣團一定是高氣壓?
  167. 21:57:IP=203.66.245.246:-1 from Taipei(tw)2:如何判斷兩物\"摩擦起電\"後,誰帶正電?誰帶負電?
  168. 21:57:IP=182.233.193.86:-1 from Tucheng(tw)1:法線加速度&曲線運動
  169. 21:57:IP=115.82.17.24:-1 from Taipei(tw)1:作功\
  170. 21:57:IP=1.200.35.176:-1 from Tucheng(tw)1:斜面的日常生活運用
  171. 21:57:IP=123.125.71.56:-1 from BEIJING(cn)1:為何波前與波速垂直?
  172. 21:56:IP=64.233.172.212:-1 from Saint Louis(us)1:以玻璃小彈珠當凸透鏡,如何求其焦距?
  173. 21:56:IP=36.225.77.215:-1 from Taipei(tw)1:什麼是〝光壓〞啊?
  174. 21:54:IP=42.72.91.114:-1 from Tucheng(tw)1:有關摩擦力一問
  175. 21:54:IP=223.136.137.101:-1 from Tainan(tw)2:整流電路的Vpp 與 Vrms關係
  176. 21:54:IP=218.173.171.188:-1 from Taipei(tw)1:三聚氰胺是不是聚合物
  177. 21:54:IP=118.160.101.135:-1 from Taipei(tw)2:錫箔紙傳熱
  178. 21:54:IP=36.231.96.109:-1 from Taipei(tw)1:作功\的定義
  179. 21:53:IP=27.246.70.112:-1 from Tucheng(tw)1:如何將螢幕投影在空氣中
  180. 21:53:IP=182.233.201.124:-1 from Touliu(tw)1:絕熱膨脹與自由膨脹
  181. 21:52:IP=123.125.71.25:-1 from BEIJING(cn)1:有關電路短路的問題
  182. 21:52:IP=101.12.101.9:-1 from Tucheng(tw)1:什麼是可逆或不可逆
  183. 21:52:IP=36.225.32.20:-1 from Taipei(tw)1:水流於漸縮坡道的流量計算?
  184. 21:51:IP=180.217.94.218:-1 from Tucheng(tw)2:可逆與不可逆程序的熱量
  185. 21:51:IP=1.175.168.91:-1 from Tucheng(tw)1:功\
  186. 21:50:IP=134.208.58.168:-1 from Tucheng(tw)1:簡諧運動(考慮彈簧質量)
  187. 21:50:IP=66.249.69.182:-1 from Mountain View(us)1:反應時間:會發生車禍嗎?
  188. 21:50:IP=1.160.33.232:-1 from Tucheng(tw)1:為什麼鍋中鍋的水無法沸騰?
  189. 21:50:IP=220.143.19.162:-1 from Taipei(tw)1:渦電流
  190. 21:50:IP=114.137.60.73:-1 from Taipei(tw)1:圓周運動加速度公式問題
  191. 21:50:IP=39.8.39.148:-1 from Taipei(tw)1:等速率圓周運動會做變加速度運動嗎?
  192. 21:50:IP=114.32.230.248:-1 from Hsinchu(tw)1:紙蜻蜓的旋轉原理
  193. 21:49:IP=64.233.172.204:-1 from Saint Louis(us)3:壓力的單位及換算
  194. 21:49:IP=124.218.75.60:-1 from Taipei(tw)3:何謂視覺疲勞?
  195. 21:48:IP=118.163.134.243:-1 from Taipei(tw)1:如何計算浴室抽風機風量是否足夠
  196. 21:48:IP=220.181.108.116:-1 from BEIJING(cn)2:水管裡的氣泡∼
  197. 21:47:IP=118.163.36.237:-1 from Taipei(tw)1:變壓器傳輸電路的電阻
  198. 21:47:IP=180.217.85.214:-1 from Tucheng(tw)2:請問光電效應中,光強度的問題
  199. 21:46:IP=117.19.204.245:-1 from Taipei(tw)1:關於靜電的問題
  200. 21:46:IP=1.34.100.2:-1 from Taipei(tw)1:有關外加電場以及水分子
  201. 21:45:IP=42.77.114.82:-1 from Tucheng(tw)1:高壓傳送和歐姆定律
  202. 21:45:IP=114.46.79.55:-1 from Taipei(tw)1:質能互換的疑惑
  203. 21:45:IP=114.40.238.172:-1 from Pingtung(tw)1:兩物體浮力會不同?
  204. 21:45:IP=140.125.32.79:-1 from Y羹nlin(tw)1:MOSFET C-V問題
  205. 21:44:IP=140.116.130.137:-1 from Tainan(tw)1:Fluid
  206. 21:44:IP=123.125.71.109:-1 from BEIJING(cn)1:台灣跟日本的溫度
  207. 21:44:IP=123.204.25.2:-1 from Taichung(tw)1:向心力的問題
  208. 21:43:IP=114.40.233.151:-1 from Taipei(tw)1:物體在地心的重量
  209. 21:43:IP=39.9.161.124:-1 from Taipei(tw)1:力平衡問題
  210. 21:41:IP=123.232.217.139:-1 from SHANDONG(cn)1:白努力..
  211. 21:41:IP=114.136.194.252:-1 from Taipei(tw)1:熱力第二定律之Kelvin-Planck statement
  212. 21:41:IP=111.83.100.103:-1 from Tucheng(tw)1:凡得瓦力
  213. 21:40:IP=101.15.214.112:-1 from Tucheng(tw)1:磁場方向
  214. 21:40:IP=140.116.49.123:-1 from Tainan(tw)1:電感充放電
  215. 21:39:IP=123.125.71.53:-1 from BEIJING(cn)1:關於等效電路一問
  216. 21:39:IP=111.83.10.193:-1 from Tucheng(tw)1:光的顏色由頻率還是波長決定?