Section outline

  • A sign partially submerged in water, displaying text that reflects clearly in the water.

    The designers of this sign used the fact that light can reflect off of many surfaces, including water, to make the sign legible. It takes a bit of thought, but words can be written in such a way that their reflection is legible, even though the words themselves are not. 
    ::这一标志的设计者们利用光能反射包括水在内的许多表面这一事实来使标志可以辨认。 它需要一些思考,但文字可以写得能够让人看得清,即使文字本身不是。

    Reflection of Light
    ::光反射

    The Reflection Of Light With Incident And Reflected Rays Near A Barrier.

    The Law of Reflection
    ::反思法

    When a light ray strikes a reflecting surface, the angle of incidence (measured from the normal line) is equal to the angle of reflection (also measured from the normal line). This is called the Law of Reflection .
    ::当光线照射反射表面时,(从正常线线测量的)事件角度等于反射角度(也从正常线测量的),这称为反射法则。

    If the reflecting surface is a very smooth surface, the reflection will be a  regular reflection, in which the light rays maintain their position relative to each other and objects will be visible and identifiable in the reflected image. If the reflecting surface is rough, the reflection will be a  diffuse reflection, and objects will not be visible or identifiable in the reflection. When you are considering the size of things on the scale of of light, even surfaces that appear smooth may be very rough in terms of light waves, and most surfaces produce diffuse reflection .
    ::如果反射表面是一个非常光滑的表面,反射将是一次定期反射,在反射中,光线保持彼此相对的位置,物体在反射图像中是可见的和可识别的。如果反射表面是粗糙的,反射将是弥散的反射,物体在反射中是看不见的或可识别的。当你考虑光的大小时,即使表面看起来光滑,光波也非常粗糙,大多数表面产生散射反射。

    The Law Of Reflection With Angles Of Incidence And Reflection On Smooth And Rough Surfaces.

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

    The images that appear in a plane (flat) mirror are reversed in some ways and not reversed in other ways.  In the image below, the man's right hand is labeled. The same hand in the mirror image, however, looks like a left hand. While the left and right of the image are reversed, the top and bottom of the image are not. 
    ::平面( 平面) 镜中显示的图像以某些方式被倒转, 而不是以其他方式倒转。 在下面的图像中, 将人的右手贴上标签 。 然而, 镜中图像中的同一只手看起来像左手 。 虽然图像的左侧和右侧被倒转, 但图像的上部和下部却不是 。

    A young man facing a mirror, labeled with left and right hand indications.

    In the simulation below, the young man is getting ready for the prom. He needs to stand at a particular and have the mirror be a particular length to be able to view his entire body. Rays of light are emerging from various light sources in the room and bouncing off him into the mirror. Play around with rays from different locations, try different mirror lengths, and see what you can discover about the reflection of light in a mirror.
    ::在下面的模拟中,年轻人正在准备参加舞会。 他需要站在一个特定的位置,让镜子长得特别长才能看清他的整个身体。 光线正在从房间里的各种光源中涌现出来,然后跳进镜子中。 与不同地点的射线玩耍,尝试不同的反射长度,看看你能从镜子中看到什么光的反射。

     

    Summary
    ::摘要

    • The law of reflection states that, when a light ray strikes a reflecting surface, the angle of incidence (measured from the normal line) is equal to the angle of reflection (also measured from the normal line).
      ::反射法则规定,当光线照射反射表面时,(从正常线测量的)事件角度等于反射角度(也从正常线测量的)。
    • If the reflecting surface is a very smooth surface, the reflection will be regular, in which the light rays maintain their position relative to each other.
      ::如果反射表面是一个非常平滑的表面,反射将是正常的,在反射中,光线保持彼此相对的位置。
    • If the reflecting surface is rough, the reflection will be diffuse and objects will be distorted in the reflection.
      ::如果反射表面粗糙,反射面会散开,物体反射时会扭曲。
    • Images in a plane mirror are reversed left and right but not reversed top and bottom.
      ::平面镜中的图像向左和向右反转,但不向上和向下反转。

    Review
    ::回顾

    1. How does regular reflection differ from diffuse reflection?
      ::经常反省与分散反省有何不同?
    2. If a light ray strikes a mirrored surface at an angle of 25° to the surface, what is the angle of incidence?
      ::如果光射线以25度角到表面照射反面表面,发生角度是什么?
    3. For problem #2, what will be the angle of reflection?
      ::对于问题2, 什么是反省的角度?
    4. A dry cement road is a diffuse reflector.  When it rains, the water fills in all the little holes and cracks in the cement road and it becomes a smooth regular reflector.  At night, when you are depending on the light from your headlights to show you the lines on the road, a wet road becomes much darker and it is more difficult to see the lines.  Explain why this occurs.
      ::干水泥路是一个分散反射器。 当下雨时,水会填满水泥路的所有小洞和裂缝,并成为光滑的定期反射器。 在晚上,当你仰赖灯光向您展示道路的线路时,湿道会变得更暗,更难看到线路。请解释为什么会发生这种情况。

    Explore More
    ::探索更多

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

     

    1. Both the angle of incidence and the angle of reflection are measured from the _________. 
      ::频率角度和反射角度均从 ° 测量。
    2. In reflection, the angle of incidence _________  the angle of reflection. 
      ::反射时, 事件角度 反射角度 。