Reflection and Refraction

When the phrase "ray of light" is used, it often means the same as "line of sight". In this lab, the "laws" of reflection and refraction are to be studied by using the equivalence of these two ideas.

当使用“光束”这一短语时，通常意味着“视线”。“反射”和“折射”定律将通过这些两个概念的等价性来研究。

Tape a plain sheet of paper to the piece of cardboard supplied. Draw a line across the center of the paper and place the mirror along this line. Support the mirror by fastening it to a wooden block. Try to keep the mirror line from moving during the experiment.

将提供的硬纸板上贴一张白纸。在纸上画一条横贯中心的线，并将镜子沿此线放置。用木块将镜子固定好。尝试在实验过程中保持镜面线不移动。

Place a pin A about 3 inches in front and toward one side of the mirror. Place a second pin B about an inch from the mirror near the center of the page. Sighting along the table top, place a third pin C so that it lines up with both the second pin and the mirror image of the first pin (see diagram). These pins define the line of sight or light ray in this case.

将一个图钉A放在镜面前约3英寸处并向一侧放置。将第二个图钉B放在离镜面约1英寸的位置，接近页面的中心。沿桌面视线，放置第三个图钉C，使其与第二个图钉和第一个图钉的镜像对齐（见图）。这些图钉定义了此次的视线或光路。

Remove the pins and mirror, draw in the rays, measure and record the angles. What is your conclusion? Repeat the above procedure using a different position for the pins to get a new set of data.

取下针和镜子，画出光线，测量并记录角度。你的结论是什么？用不同的位置重新进行上述步骤以获得一组新的数据。

Start with a new, plain sheet of paper taped to the cardboard and make a set of perpendicular lines that cross near the center of the page. Place one pin O at the crossing point of the lines and place the glass cube or plate against this line with one side placed along the line .

从一张新纸上剪下一块，将其用胶带贴在硬纸板上，画出一组相互垂直的线，使它们在页面中心交叉。在交叉点放置一个针O，并将玻璃立方体或板放在该线的一侧，使其一侧沿该线放置。

Carefully trace the glass block or plate on your paper. Now place a second pin A above and to the left of the first and a third pin B against the glass and in line with the first two as seen looking through the glass. Finally, place a fourth pin C on the viewing side of the glass, in line with pin B and the images of the other pins seen through the glass.

仔细在纸上描画玻璃块或板的轮廓。现在将第二枚大头针A放在第一枚的上方和左侧，第三枚大头针B置于玻璃内，并与前两枚大头针在透过玻璃观察时处于同一直线上。最后，在玻璃的观察侧放置第四枚大头针C，使其与大头针B以及通过玻璃看到的其他大头针的像在同一直线上。

Remove the glass and pins and draw the path taken by the ray of light. Measure the angles of the incoming ray and the ray in the glass. It is standard practice to measure ray angles with respect to the normal (the perpendicular line to the entrance surface). With a protractor, measure the angles of the incoming ray and the ray you have drawn through the glass.

去掉玻璃和针，画出光线在玻璃中的路径。测量入射光线和玻璃中的光线的夹角。通常做法是将光线角度相对于法线（即入射面的垂线）来测量。用量角器测量入射光线和你画出的通过玻璃的光线的夹角。

The index of refraction of a material is defined by n = c/v where c is the velocity of light in vacuum (3 x 108 m/sec) and v is the velocity in the medium. When light is refracted at a surface, the angles of the incident and refracted rays are related by Snell's law:

介质的折射率由n = c/v定义，其中c是真空中的光速（3 x 108 m/sec），v是光在介质中的速度。当光在界面上发生折射时，入射光线和折射光线的夹角由斯涅尔定律相关联：

Since the index of refraction of air is almost one (nair = 1.00028), the index of refraction of the glass can be determined by

由于空气的折射率几乎为一（n_air = 1.00028），因此可以通过

Using a calculator or computer to determine the sines of the angles you have measured, compute the index of refraction of the glass and the speed of light in that glass.

使用计算器或计算机计算你所测量的角度的正弦值，计算玻璃的折射率以及光在该玻璃中的速率。

You will be provided with a prism which has two edges clear and one edge frosted (the base of the prism). Draw a line across a sheet of paper, place the base of the prism along this line, and carefully trace it on the paper. Place a pin A in the position shown in the figure. Sighting past A and through the prism, place another pin B about three inches from the opposite side of the prism where you can see it and line it up with A. Place a third pin C closer to the prism on the same side as B so that all three pins line up when viewed through the glass. Finally place a fourth pin on the viewing side to define the ray coming to your eye from the prism. Remove the pins and prism and draw the paths of the light rays.

您将获得一个棱镜，其两个边缘是透明的，一个边缘是磨砂的（棱镜的底面）。在纸上画一条线，将棱镜的底面沿着这条线放置，并仔细地在纸上描出其轮廓。在图中所示的位置放置一个针A。通过A点，看向棱镜内部，再在棱镜的另一侧放置另一个针B，距离棱镜约三英寸的位置，使得您可以看到B并使其与A对齐。在B所在的一侧，更靠近棱镜的位置放置第三个针C，使得当通过玻璃观察时，三个针都对齐。最后，在观察侧放置第四个针，以定义从棱镜传入您眼睛的光线路径。移除针和棱镜，并画出光线的路径。

Reflection and Refraction

Equipment: Reflection and Refraction