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  • General

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  • 横反波

    A surfer rides a massive wave at Jaws surf break in Maui, HI.

    This surfer rides a giant wave at the legendary big wave surf break known as "Jaws" in Maui, HI. Massive waves, such as this one, transfer huge amounts of .
    ::这个冲浪者骑着巨浪 在传说中的大浪冲浪突破 被称为"Jaws" 在毛伊岛,HI。大浪,例如这个, 转移了巨大的数量。

    Transverse Waves
    ::横横波

    Types of Waves
    ::波浪类型

    Water waves and the waves that travel along a rope are mechanical waves . Mechanical waves require a material medium such as water, air, or rope. Light waves, however, are electromagnetic waves and travel without a material medium. They are not mechanical waves.
    ::机械波需要水、空气或绳索等物质介质,光波是电磁波,没有物质介质,不是机械波。

    In all types of mechanical waves, energy moves from one place to another while the media carrying the wave only vibrates back and forth in position. One type of is the transverse wave . In the case of transverse waves, the movement of the medium is perpendicular to the direction of the energy movement.
    ::在所有类型的机械波中,能量从一个地方移动到另一个地方,而媒体只将波向回向和向外移动,一种是反向波,在反向波中,介质的移动与能源运动的方向是垂直的。

    A boy creating a transverse wave in a rope tied to a tree.

    In the sketch above, consider the transverse wave produced when the boy jerks one end of a rope up and down while the other end is tied to a tree.  The energy spent by the boy transfers permanently down the rope to the tree. The rope, however, only moves up and down. If we stuck a piece of tape somewhere on the rope, we would see that the particles of medium do not travel with the energy. After the wave has passed by, the piece of tape would still be in the same place it was before the wave approached. In all transverse waves, the movement media vibrates perpendicularly to the direction of wave motion, and the medium is not permanently moved from one place to another.
    ::在上文的草图中,请考虑当男孩把绳子的一端上下拉到树上,而另一端被绑在树上时产生的横跨波。男孩的能量将永久地从绳子上移到树上。然而,绳子只是向上和向下移动。如果我们在绳子上插入一块带子,我们就会看到介质的粒子不会随能量而移动。在波浪经过之后,带子仍然在波浪接近前的位置。在所有反向波波浪中,移动媒体的振动都与波动的方向垂直,介质不会从一个地方一直移动到另一个地方。

    Frequency, Wavelength, and Velocity
    ::频率、波长和速度

    Waves are identified by several characteristics. There is a center line where the medium would be if there were no wave, which is sometimes describes as the undisturbed position . The displacement of the medium above this undisturbed position is called a crest and the displacement below the undisturbed position is called a trough . The maximums of the crest and trough are equal and are called the amplitude . The distance between equivalent positions on succeeding waves is called the . The wavelength could be measured from a crest to the next crest or from a trough to the next trough, and is commonly represented with the Greek letter lambda, @$\begin{align*}\lambda\end{align*}@$ .
    ::波有几种特性。 介质有一条中线, 如果没有波, 介质就会是, 有时被描述为未扰动的位置 。 介质在此未扰动的位置之上的移位被称为顶部, 而未扰动的位置下面的移位则被称为下层。 顶层和下层的最大值相等, 也被称为振幅 。 下一波的等值位置之间的距离被称为 。 波长可以从顶部到下层, 或者从下层到下层测量, 通常用希腊字母 lamda 表示 , @$\ begin{ allign\ lambda\end{ allign}} 。

    Labeling of crest, trough, amplitude, and wavelength for transverse waves.

    The time interval required for one complete wave to pass a point is called the period . During the period of the wave, an entire wavelength from one crest to the next crest passes a position. The number of waves that pass a single position in one second is called the frequency . The period of a wave and its frequency are reciprocals of each other.
    ::一个完整波通过点所需的时间间隔称为时段。在波段期间,从一个柱子到下一个柱子的整个波长通过一个位置。一秒内通过一个位置的波数称为频率。波的周期和波的频率是对等的。

    @$$\begin{align*}f=\frac{1}{T}\end{align*}@$$
    ::@$\ begin{ leign} ffrac{ 1\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\$美元 </span> </p> <button class="play-button btn btn-success" style="float: right;" value="@s"> 播放段落 </button> <p id="x-ck12-Yzg4ZjI1MzY3NjA1ZjVlN2U3N2U3MGRhYzZlM2IzZjM.-nug"> The units for the period are seconds and the units for frequency are s <sup> -1 </sup> or <span class="x-ck12-mathEditor" data-contenteditable="false" data-edithtml="" data-math-class="x-ck12-math" data-mathmethod="inline" data-tex="%5Cfrac%7B1%7D%7B%5Ctext%7Bs%7D%7D"> @$\begin{align*}\frac{1}{\text{s}}\end{align*}@$ . This unit has also been given the name Hertz (Hz).
    ::时段的单位为秒, 频率单位为 s-1 或@$\ begin{ align_ frac{ 1\\\ text{ s\\\\\ end{ align} $。 这个单位也被命名为 Hertz (Hz) 。

    Another important characteristic of a wave is its . The wave velocity is different from the velocity of the medium; the wave velocity is the velocity of the linearly transferred energy. Since the energy travels one wavelength, @$\begin{align*}\lambda\end{align*}@$ , in one period, @$\begin{align*}T\end{align*}@$ , the velocity can be expressed as over time:
    ::一个波的另一个重要特征是波。波的速度与介质的速度不同;波的速度是线性转移能量的速度。由于能量移动一个波长, @$\ begin{ align} lambda\ end{ align} $,在一个时期,@$\ begin{ align}T\end{align} $, 速度可以表现为时间 :

    @$$\begin{align*}v=\frac{\lambda}{T}.\end{align*}@$$
    ::@ $\ begin{ ALIGN} vfrac_ lambda_ T}.\ end{ align} $

    Since period and frequency are reciprocals, the of the wave could also be expressed as @$\begin{align*}v=\lambda f\end{align*}@$ .
    ::由于时间间隔和频率是对应的,波浪也可以表示为@$\ begin{ align} v lambda f\ end{ align}$。

    Examples
    ::实例

    Example 1  
    ::例1

    A wave has a frequency of 262 Hz.  What is the time lapse between successive wave crests?
    ::海浪的频率为262赫兹。 连续波峰之间的时间间隔是多少?

    The time lapse between successive crests would be the period and the period is the reciprocal of the frequency.
    ::前后的徽章之间的时间间隔将是这一时期,而这一时期是频率的对等时间。

    @$$\begin{align*}T=\frac{1}{f}=\frac{1}{262 \ \text{s}^{-1}}=0.00382 \ \text{s}\end{align*}@$$
    ::@ $\ begin{ legin} $\ begin} legin} t\\ frac{ 1\\\ f\\ f\ f\\ frac{ 1\\\\\\\\\\\\\ text{ s\\\\\\ 0.00382\\\ text{ s\\ end{ legn{ legn} $

    Example 2  
    ::例2

    A wave has a frequency of 262 Hz has a wavelength of 1.29 m.  What is the velocity of the wave?
    ::一个波的频率为262赫兹,波长为1.29米。波的速度是多少?

      @$\begin{align*}v=\lambda f=(1.29 \ \text{m})(262 \ \text{s}^{-1})=338 \ \text{m/s}\end{align*}@$
    ::@ $\ begin{ leign} v lambda f= (1. 29\\ text{ m} (262\\ text{s}) = 338\\ text{ m/\\ end{ end{ align} $)

    Do you think you could estimate the wavelength of ocean waves just by observing how frequently they hit the boardwalk? How would the wind affect this wavelength? Play around with the PLIX Interactive below to learn more about ocean waves:
    ::你是否认为只要观察海浪撞上木板路的频率就能估计出海浪的波长? 风会如何影响波长? 与下面的PLIX互动游戏一起学习更多关于海浪的知识:

     

     

    Further Reading
    ::继续阅读

    Summary
    ::摘要

    • Mechanical waves require a material medium such as water, air, or rope.
      ::机械波需要水、空气或绳子等材料媒介。
    • In all types of mechanical waves, energy moves from one place to another while the media carrying the wave only vibrates back and forth in position.
      ::在所有类型的机械波中,能源从一个地方移动到另一个地方,而媒体的波浪只起起伏不定。
    • One type of mechanical wave is the transverse wave, in which the movement of the medium is perpendicular to the direction of the energy propagation. 
      ::一种机械波是反向波,介质的移动与能量传播的方向垂直。
    • The maximum displacement of the medium is the distance from the undisturbed position to the top of a crest, or the amplitude.
      ::介质的最大偏移是从未扰动的位置到顶部的距离或振幅。
    • The distance along the line of motion of the wave from equivalent positions on succeeding waves is the wavelength.
      ::波的运动线与后继波的等同位置的距离是波长。
    • The time interval required for one entire wave to pass a point is the period.
      ::一个整波通过点所需的时间间隔是该周期。
    • The number of periods per second is the wave's frequency.
      ::每秒的周期数是波的频率 。
    • The period of a wave and its frequency are reciprocals of each other.
      ::海浪的周期和频率是相互对等的。
    • The velocity of the wave's energy transfer is given by  @$\begin{align*}v=\lambda f\end{align*}@$  or  @$$\begin{align*}v=\frac{\lambda}{T}.\end{align*}@$$
      ::波的能量传输速度由 @ $\ begin{ aliign} vlambda f\ end{ aliign} 或 @ $\ begin{ liign} vfrac_lambda} 给出 。\ end{ align} $

    Review
    ::回顾

    1. When a guitar string is plucked, in what direction does the wave travel? In what directions does the string vibrate?
      ::当吉他弦被拔出时,波浪会向哪个方向飞去?


      ::当吉他弦被拔出时,波浪会向哪个方向飞去?

    2. If the speed of a wave is 2.5 × 10 3 m/s and has a wavelength of 5.80 × 10 -7 m, what is its frequency?
      ::如果波的速度是2.5×103米/秒,波长为5.80×10-7米,其频率是多少?


      ::如果波的速度是2.5×103米/秒,波长为5.80×10-7米,其频率是多少?

    3. A wave has a frequency of 350 Hz has a wavelength of 3.9 m.  What is the velocity of the wave?
      ::海浪的频率为350赫兹,波长为3.9米。波的速度是多少?


      ::海浪的频率为350赫兹,波长为3.9米。波的速度是多少?

    Explore More
    ::探索更多

    Use this resource to answer the questions that follow.  
    ::使用此资源回答下面的问题 。

     

     

    1. What is the distance between the equilibrium position and trough called?
      ::平衡位置和槽之间的距离叫什么?
    2. What are the fundamental units of Hertz?
      ::赫兹的基本单位是什么?
    3. What is the relationship between frequency and speed?
      ::频率和速度之间的关系是什么?