Properties of Wave Pulses and Waves · 波脉冲与波的性质
| English | 中文 | Pinyin · 拼音 |
|---|---|---|
| wave/weɪv/ | 波 | bō |
| transverse wave/trænsˈvɜːs weɪv/ | 横波 | héng bō |
| longitudinal wave/ˌlɒŋɡɪˈtjuːdɪnl weɪv/ | 纵波 | zòng bō |
A stadium "Mexican wave" — people stay put, the wave races round
- In a Mexican wave, each fan just stands and sits — yet a wave sweeps around the whole stadium.
- No person travels with it; only the pattern moves.
- That's the heart of a wave 波: it carries energy from place to place, but not matter.
- Understanding this one idea unlocks sound, light and every ripple.
体育场里的"人浪"——人待在原地,浪却飞速绕场
- 在人浪里,每个球迷只是站起再坐下——可一道浪却扫过整个体育场。
- 没有人随它移动;只有那个图案在动。
- 这正是波的核心:它把能量从一处带到另一处,却不带走物质。
- 理解这一个概念,就解开了声、光和每一道涟漪。
Waves carry energy, not matter
- A wave is a disturbance that travels, moving energy without moving the medium along with it.
- A single bump is a pulse; a repeating disturbance is a continuous wave.
- Drop a stone in a pond: the ripple spreads outward, but the water just bobs up and down.
- The floating leaf goes up and down, not outward — proof that matter stays put.
波传递能量,而非物质
- 波是一种传播的扰动,它移动能量,却不把介质一起带走。
- 单个凸起是一个脉冲;重复的扰动是连续的波。
- 往池塘里丢一块石头:涟漪向外扩散,但水只是上下起伏。
- 漂浮的叶子上下起伏,而非向外——证明物质待在原地。
A travelling wave carries: · 行波携带：
A wave transfers energy; the medium only vibrates in place. · 波传递能量；介质仅在原地振动。
As a water wave passes, a floating leaf mostly bobs up and down rather than travelling with the wave. · 水波经过时，漂浮的叶子主要上下浮动，而非随波迁移。
The medium vibrates in place; the leaf shows the matter does not travel with the wave. · 介质原地振动；叶子的运动表明物质不随波迁移。
Transverse and longitudinal
- In a transverse 横波 wave, the medium vibrates perpendicular to the direction of travel (light, water ripples).
- In a longitudinal 纵波 wave, it vibrates along the direction of travel (sound, a pushed slinky).
- Both move energy forward, just with different particle motions.
- Only transverse waves can be polarised (lesson 14.3).
横波与纵波
- 在横波中,介质在垂直于传播方向上振动(光、水波)。
- 在纵波中,它在沿传播方向上振动(声、被推的弹簧)。
- 两者都把能量向前移动,只是粒子运动方式不同。
- 只有横波才能被偏振(第 14.3 节)。
Transverse or longitudinal · 横波或纵波
Switch between transverse and longitudinal and watch how the particles move relative to travel. · 切换横波与纵波，观察质点相对于传播方向的运动。
In a transverse wave, the medium vibrates: · 在横波中，介质振动方向：
Transverse means the vibration is perpendicular to the travel direction. · 横波指振动方向垂直于传播方向。
Sound is a longitudinal wave. · 声波是纵波。
Sound vibrates the air along the direction of travel — longitudinal. · 声波沿传播方向引起空气振动——属于纵波。
Select all · 所有 true statements about waves. · 选择关于波的所有正确陈述。
Waves transfer energy, come in transverse and longitudinal kinds — but never carry the medium along. · 波传递能量，分为横波和纵波两类——但从不携带介质移动。
Speed depends on the medium
- A wave's speed is set by the material it travels through, not by how it was made.
- Sound travels faster in water than in air, and faster still in steel.
- Light travels fastest of all in a vacuum, slowing in glass or water.
- Change the medium and the speed changes; the frequency stays the same (set by the source).
速率取决于介质
- 波的速率由它所穿过的材料决定,而非它是如何产生的。
- 声在水中比在空气中传得快,在钢中更快。
- 光在真空中传得最快,在玻璃或水中变慢。
- 换介质速率就变;频率保持不变(由波源决定)。
A wave's speed is set by the ____ it travels through. · 波速由其所通过的 ____ 决定。
The medium (air, water, steel) sets the wave speed. · 介质（空气、水、钢等）决定了波速。
A wave transfers energy, not matter. The medium (water, air, the crowd) only vibrates in place — it does not travel along with the wave. Confusing the moving pattern with moving matter is the classic wave misconception.
波传递能量,而非物质。介质(水、空气、人群)只是原地振动——它不随波一起移动。把移动的图案和移动的物质弄混,是经典的波误解。
You flick one end of a long rope up and down once, sending a pulse along it.
- The pulse (and its energy) travels to the far end.
- Each bit of rope only moves up and down — it does not slide toward the other end. That is a transverse wave.
你把一根长绳的一端上下抖动一次,沿绳送出一个脉冲。
- 脉冲(及其能量)传到远端。
- 每一小段绳只上下运动——它不会滑向另一端。这是一个横波。
A wave carries energy, not matter — the medium only vibrates in place. Transverse waves vibrate across the direction of travel (light, ripples); longitudinal waves vibrate along it (sound). A wave's speed is set by its medium.
波传递能量,而非物质——介质只是原地振动。横波在垂直于传播方向上振动(光、涟漪);纵波沿传播方向振动(声)。波的速率由它的介质决定。