运弓当一个弓子拉过弦的时候,琴弦振动呈凸透镜状,宛如一条光滑的带子,但这是一种视错觉。事实上,弓子下面的琴弦很接近于形成了折线状——一个被亥姆霍兹注意的现象。用拍慢镜头的高速摄影机能够显示这一折线(如图1所示),折点是沿凸透镜状轨迹在弦的两端之间延伸的。这种弓在弦上的“粘一滑”运动,虽然有点象粉笔在黑板 Bowing When a bow pulls strings, the strings vibrate lenticularly, like a smooth band, but this is an optical illusion. In fact, the string under the bow was very close to the fold line - a phenomenon that was noticed by Helmholtz. The polyline (shown in Figure 1) can be displayed using a slow-motion high-speed camera that extends along the lenticular trajectory between the two ends of the chord. The “stick-slip” movement of this bow on the chord, albeit a bit like a chalk on a blackboard