章节大纲

  • 常规

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  • 光的反射

    Lesson Objectives
    ::经验教训目标

    • Demonstrate that light travels in a straight line until it strikes an object or travels from one medium to another.
      ::证明光线以直线运行,直到击中物体或从一个介质到另一个介质。
    • Demonstrate that light can be reflected, refracted, and absorbed.
      ::证明光线可以被反射、分解和吸收。

    Lesson Vocabulary
    ::词汇表课程

    • light - a form of energy that travels in waves and can move through empty space where there is no air
      ::光光光 - 一种能量形式,在波浪中穿行,可以在没有空气的空空空空间中移动
    • transmit - pass through
      ::- 通过
    • reflection - bouncing back of light from a surface
      ::- 反射反射从表面光线反弹背面
    • refraction - bending of light
      ::折射 - 灯光弯曲
    • absorb - light is taken in
      ::- 吸收 - 光被吸收

    Reflection of a sign in water
     

    Check out this sign. The sign is upside down. So how can you can still read it? The people who made this sign used science to make it possible to read it upside down. They knew that light can reflect off of many surfaces. Even water can reflect light. Think about how this sign was made. The words are written so that their reflection can be read.  
    ::检查这个标记。 这个标记是倒着的。 你还能读它吗? 做这个标记的人用科学来读它。 他们知道光能反射许多表面。 甚至水也能反射光。 想想这个标记是如何形成的。 文字是写好的, 以便他们能读懂。

    Reflection of Light
    ::光反射

    Wave reflecting off a barrier
     

    The Law of Reflection
    ::反思法

    Light rays strike a reflecting surface. They are then reflected back. You can predict the angle of the reflected light. Imagine a ball bouncing off a surface. Light can do the same thing. That is, assuming the surface is shiny. So how do you know where light will go after it strikes a shiny surface? It depends on how the light initially strikes the shiny object. Light does not always go straight toward a surface. Therefore, not all light bounces straight back. Sometimes, light can hit a surface at an angle. The angle at which it strikes the surface tells us how it will bounce off. While light is different to a ball, they react in a similar manner.
    ::光线照射反射表面, 然后反射。 您可以预测反射光的角。 想象一个反射光的角。 想象一个球从表面跳下。 光也可以做同样的事情。 假设表面是亮亮的, 也就是假设表面是亮的。 所以, 你如何知道光线在闪亮的表面后会到哪里去? 它取决于光线最初如何撞击闪亮的物体。 光不总是直向表面。 因此, 光不是全部反射。 有时, 光可以直反射到一个角度。 光线撞击一个角度时, 它撞击表面的角告诉我们它会如何反弹。 虽然光与球不同, 它们的反应方式相似。

    Many sports rely on knowledge of reflection. Pool players know a lot about reflection. They take great care when they strike the pool ball. They need it to go to a certain place. They know the angle it will hit the side of the pool table. Knowing this, they can predict how the ball will travel. The diagram above shows how light rays travel as they strike a surface. Incoming and outgoing light rays always react in a similar but opposite way. The angles they hit a surface are similar but opposite the angle after. This action is known as the Law of Reflection.
    ::许多运动依靠反射知识。 球员对反射非常了解。 当他们击球时, 他们非常小心。 他们需要它去某个地方。 他们知道球会击中球桌边的角。 知道这一点, 他们可以预测球会如何行走。 上面的图表显示光线在撞击表面时如何行走。 进出的光线总是以相似但相反的方式反应。 他们撞到球面的角是相似的, 但与后面的角度相反。 这个动作被称为“ 反射法则 ” 。

    Reflection needs a very smooth surface to work well. When light strikes a surface that is smooth, it is called  regular   reflection.  The way light rays reflect can be predicted. This also results in an image that you can see clearly.
    ::反射需要一个非常平滑的表面才能很好地工作。 当光线击中一个光滑的表面时, 它被称为定期反射。 光线反射的方式可以预测。 这也可以产生一个您可以清楚地看到的图像 。

    What if the surface that light strikes is not smooth? In those cases, the reflection will be a  diffuse   reflection.   The objects may not be seen clearly. Instead, they may look fuzzy or blurred.
    ::如果光撞击的表面不平滑呢?在这些情况下,反射将是散射反射。物体可能无法清晰地看到。相反,它们可能看起来模糊或模糊。

    Comparison of the reflection off a rough and off a smooth surface
     

    Left and Right Reversal in a Plane Mirror
    ::在平面镜中向左和向右逆向

    You have seen your own reflection in a mirror. The person looking back at you looks just like you.  Where does that reflected person appear to be standing? Yes, they appear to be on the other side of the mirror. That is really strange to think about, but very cool. Have you ever waved at your reflection in a mirror?  The reflected image will wave back at you.
    ::你曾经在镜子里看到你自己的反射。回望你的人看起来和你一样。反射者似乎站在哪里?是的,他们似乎站在镜子的另一边。这很奇怪,但很酷。你有没有用镜子向你的反射挥手过?反射图像会回荡在你身上。

    Here is something to try next time you stand in front of a mirror. Wave to your reflection with your right hand. What hand do you think the reflection will wave back with? The same hand? A different hand? You will notice something interesting. The reflection waves back with the hand on the same side as you, but it is their left hand. The image in a reflection is reversed.
    ::下次你站在镜子前的时候, 这里要尝试一些东西。 用右手向反射挥手。 你认为反射会用哪只手向后挥手? 同一只手? 另一只手? 你会注意到一些有趣的东西。 反射会用手向后挥手, 与你同侧, 但反射是他们的左手。 反射中的图像是倒转的 。

    This is just like the image of the sign above. Light rays strike flat shiny surfaces and are reflected. The reflections are reversed. Next time you see an ambulance look at the word on the front of it? Why do you think it appears this way? 
    ::这就像上面标志的图像。 光线照亮平坦闪亮的表面, 并被反射。 反射反转。 下次你看到救护车看到前面的字眼时, 你为何认为它会这样看?

    Right and left reversal in a mirror

     

    Lesson Summary
    ::经验教训摘要

    • The law of reflection can be used to predict how light will be reflected. 
      ::反射法则可用于预测如何反映光线。
    • If the reflecting surface is a very smooth surface, the reflection will be regular and the image viewed will be clear.
      ::如果反射表面是一个非常平滑的表面,反射将是正常的,所看到的图像将是清晰的。
    • If the reflecting surface is rough, the reflection will be diffuse and the image you see will be distorted.
      ::如果反射表面粗糙,反射面就会散开,你看到的图像就会被扭曲。
    • Images in a plane mirror are reversed left and right. They are not reversed top and bottom.
      ::平面镜中的图像会向左和向右反转。 它们不会向上和向下反转 。

    Lesson Review Questions
    ::经验回顾问题

    1. How does regular reflection differ from diffuse reflection?
      ::经常反省与分散反省有何不同?