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  • 波浪相互作用

    A woman is shouting toward a large building, attempting to create an echo.

    Did you ever hear an echo of your own voice? An echo occurs when bounce back from a surface that they can’t pass through. The woman pictured here is trying to create an echo by shouting toward a large building. When the sound waves strike the wall of the building, most of them bounce back toward the woman, and she hears an echo of her voice. An echo is just one example of how waves interact with matter.
    ::你曾经听到过自己声音的回声吗?回声从他们无法穿越的表面反射出来时就会发生。 这里所描绘的女人正试图通过对大建筑物的呼喊来创造回声。 当声波冲击建筑物的墙壁时,他们中的大多数都反弹到女人身上,她听到她声音的回声。 回声只是波与物质互动的一个例子。

    How Waves Interact with Matter
    ::如何波波与物质互动

    Waves interact with matter in several ways. The interactions can occur when waves pass from one medium to another, meet a barrier, or spread out around an edge or gap in a medium. Some examples of interactions are , , and diffraction . Each type of interaction is described in detail below. 
    ::海浪以几种方式与物质相互作用。波浪从一个介质传到另一个介质,遇到屏障,或者在介质的边缘或间隙散布。一些相互作用的例子是 、 和 分解。每种类型的相互作用都详述如下。

    Reflection
    ::反射反射

    An echo is an example of wave reflection. Reflection occurs when waves bounce back from a surface they cannot pass through. Reflection can happen with any type of waves, not just sound waves. For example, light waves can also be reflected. In fact, that’s how we see most objects. Light from a light source, such as the sun or a light bulb, shines on the object and some of the light is reflected. When the reflected light enters our eyes, we can see the object.
    ::反射是波浪反射的一个例子。 反射发生在波浪从无法穿透的表面反射回来时。 反射可以在任何类型的波中发生, 而不仅仅是声波。 例如, 光波也可以被反射。 事实上, 光波也可以被反射。 我们就是这样看待大多数物体的。 从阳光或灯泡等光源发出的光照耀着物体和一些光线。 当反射光进入我们的眼睛时,我们可以看到物体。

    Reflected waves have the same and frequency as the original waves before they were reflected. However, the direction of the reflected waves is different. When waves strike an obstacle head on, the reflected waves bounce straight back in the direction they came from. When waves strike non- transparent obstacle at any other angle, they bounce off the surface in a different direction. This is illustrated in the Figure . In this diagram, waves strike a wall at an angle measured from the ‘normal’ line perpendicular to the surface of the object, called the angle of incidence. The waves are reflected at the same size angle, called the angle of reflection, measured from the other side of the normal line. Notice that both angles are measured relative to a line that is perpendicular to the surface.
    ::反射波与反射波在反射前的原波具有相同的频率和频率。 但是, 反射波的方向不同。 当波浪撞上障碍头时, 反射波会直接反弹回向它们从那里来的方向。 当波浪撞上其他任何角度时, 反射波会从表面反射到不同的方向。 图中说明了这一点。 在本图中, 波向墙壁的角从“ 正常” 线直向物体的表面, 称为事件角度。 海浪的反射角度相同, 从正常线的另一侧测量的反射角度。 注意两个角度都是相对于与表面垂直的线测量的。

    Wave reflection, illustrating angles of incidence and reflection with a wall.

     

     

     

     

     

     

    Refraction
    ::折中

    Refraction is another way that waves interact with matter. Refraction occurs when waves bend as they enter a new medium at an angle. You can see an example of refraction in the Figure . Light bends when it passes from air to water or from water to air. The bending of the light traveling from the fish to the man’s eyes causes the fish to appear to be in a different place from where it actually is.
    ::折射是波体与物质相互作用的另一种方式。 当波体从一个角度进入新介质时,波体弯曲时会发生折射。 您可以在图中看到一个折射的例子。 当从空气到水或从水到空气时,光线弯曲。 光线从鱼到人眼睛的弯曲使鱼看起来与实际位置不同。

    Refraction of light as it passes from air to water, affecting perceived fish location.

    Waves bend as they enter a new medium because they start traveling at a different speed in the new medium. For example, light travels more slowly in water than in air. This causes it to refract when it passes from air to water or from water to air.
    ::海浪在进入新介质时弯曲,因为它们开始以不同速度在新介质中行驶。例如,光在水中行走比在空气中行走慢。当从空气到水或从水到空气中行走时,光会折曲。

    Q: Where would the fish appear to be if the man looked down at it from straight above its actual location?
    ::问:如果那人从鱼的实际位置上方直直看鱼,鱼会在哪里呢?

    A: The fish would appear to be where it actually is because refraction occurs only when waves (in this case light waves from the fish) enter a new medium at an angle other than 90°.
    ::A:鱼似乎处于实际位置,因为只有在海浪(在此情况下,鱼的光波)以90度以外的角进入新介质时,才会发生反射。

    Diffraction
    ::D. 违法行为

    Did you ever notice that you can hear sounds around the corners of buildings even though you can’t see around them? The Figure shows why this happens. As you can see from the figure, sound waves spread out and travel around obstacles. This is called diffraction . It also occurs when waves pass through an opening in an obstacle. All waves may be diffracted, but it is more pronounced in some types of waves than others. For example, sound waves bend around corners much more than light does. That’s why you can hear but not see around corners.  
    ::你是否注意到,即使你看不到建筑物的角落周围的声音,你也能听到这些声音?图表显示了发生这种情况的原因。正如你从图中可以看到的,声音波向外扩散,并绕着障碍物而行。这被称为“分解 ” 。 当波浪通过一个障碍物时,它也会发生。所有波浪都可能变幻莫测,但在某些类型的波浪中,它比其他的波浪更明显。例如,声波在角周围的曲折比光线要多得多。这就是为什么你能听到但看不到角落的原因。

    Sound waves diffracting around a corner, demonstrating wave interactions.

    For a given type of waves, such as sound waves, how much the waves diffract depends on the size of the obstacle (or opening in the obstacle) and the of the waves. 
    ::对于某种类型的波,例如声波,波的大小取决于障碍的大小(或障碍的开口)和波的大小。

    Comparison of diffraction effects with openings larger and equal to the wavelength of waves.

    The Figure shows how the amount of diffraction is affected by the size of the opening in a barrier. There is more diffraction when the width of the opening is roughly the same size as the wavelength and less diffraction when the opening is larger than the wavelength. Note that the wavelength of the wave is the between the vertical lines.
    ::图中显示了在屏障中,碎片的大小会如何影响开口的大小。当开口的宽度与波长大致相同,而开口比波长大时的偏差则较小。请注意,波的波长是垂直线之间的波长。

     

     

     

    Summary
    ::摘要

    • Three ways that waves may interact with matter are reflection, refraction, and diffraction.
      ::海浪与物质相互作用的三种方式是反射、折射和折射。
    • Reflection occurs when waves bounce bounce off a surface that they cannot pass through.
      ::反射发生于波浪反弹从它们无法穿透的表面反射时。
    • Refraction occurs when waves bend as they enter a new medium at an angle and start traveling at a different speed.
      ::当海浪弯曲以一个角度进入新介质并开始以不同速度行驶时,就会发生折射。
    • Diffraction occurs when waves spread out as they travel around obstacles or through openings in obstacles.
      ::当波浪在障碍物周围或通过障碍物的开口漫漫时,就会发生破坏行为。

    Review
    ::回顾

    1. What is reflection? What happens if waves strike a reflective surface at an angle other than 90°?
      ::反射是什么?如果波浪以90度以外的角撞击反射表面,会发生什么?
    2. Define refraction. Why does refraction occur?
      ::定义折射。 为什么会发生折射?
    3. When does diffraction occur? How is wavelength related to diffraction?
      ::折射何时发生?波长如何与折射相关?