英语流利说 Level5 Unit2 Part2 Light a
People have wondered about the nature of light and color since ancient times.
Some people thought that light came from the eye rather than coming into the eye. 来自眼睛 而不是进入眼睛
To see, light was projected from our eyes to illuminate things as we look at them.
Now we know that what we see is mostly reflected light, like the light from the moon which is reflected sunlight.
Light comes from a light source, such as the Sun, and either enters our eyes directly or after it has reflected off something.
(What is the source of the light we see when we look at the moon?) the sun
(Besides the sun, what is another example of a direct light source? ) a fire or a flashlight
(To illuminate something means?) to make it visible
wonder about 想知道
nature n.自然界; 大自然; 自然; 自然方式; 天性; 本性; 性格;本质
project v.规划; 计划; 拟订方案; 预测; 预计; 推想; 放映; 投射; 投影;
illuminate v.照明; 照亮; 照射; 阐明; 解释; 用彩灯装饰;
mostly adv.主要地; 一般地; 通常;
reflected light 反射光; 反光; 反射光線; 反射的光线;
light source 光源; 光源类型; 灯源; 发光源;
reflect off 反射出
visible adj.看得见的; 可见的; 明显的; 能注意到的;
flashlight n.手电筒; 手电;
In 1666, Sir Isaac Newton showed that when light passes through a prism, it separates into all the other colors. 当光通过棱镜时，它会分离为所有其他颜色
This clearly demonstrated that light is composed of many different colors.
The difference between colors is due to their wavelength.
A prism separates light into different colors because each color has a different wavelength.
The angle at which a color bends in a prism depends on its wavelength.
(What determines the color of light?) its wavelength
(What can separate light into its component colors?) A prism
(The angle at which a color bends in a prism) depends on its wavelength
passes through 穿过; 经历; 经验; 遭受;
prism n.棱柱体; 棱柱; 棱镜; 三棱镜;
separate v.(使) 分开，分离; 分割; 划分; (使) 分离，分散; 隔开; 阻隔;
all the other 所有其他
demonstrat v.证明; 证实; 论证; 说明; 表达; 表露; 表现; 显露; 示范; 演示;
compose of v.组成，构成(一个整体); 作曲; 创作(音乐); 撰写(信函、讲稿、诗歌等);
wavelength n.波长; (广播电台等占用的) 频道，波道;
component adj.成分的; 组成的; 合成的; 构成的;
Colors with shorter wavelengths bend more than colors with longer wavelengths.
This explains why red light bends less than yellow light.
The reason is because its wavelength is longer.
Of all the visible colors, violet light has the shortest wavelength, so it bends the most.
(Of the visible colors, which color has the shortest wavelength? ) violet
(A prism separates light into its component colors.)
(Each color is a single wavelength of light.)
violet adj.紫罗兰色的; 蓝紫色的;
If you have ever painted, you know that different colors can be combined to create new colors.
For example, if you add white to a color, you lighten it.
However the three primary colors, red, blue and yellow, can not be made by mixing other colors.
It isn't possible to mix any combination of colors to create red, blue or yellow.
Mixing two primary colors creates a new secondary color, such as purple, which is made by mixing blue and red.
Mixing three primary colors creates a tertiary color, such as brown or grey .
(Which colors can not be created by combining other colors?) the primary colors
(What happens to a color if you add white to it?) It gets lighter
(The primary colors can not be created by mixing other colors.)
(How can you create a secondary color?) mixing two primary colors
combine v.(使) 结合，组合，联合，混合; 兼有; 兼备; 使融合(或并存); 同时做(两件或以上的事); 兼做; 兼办;
lighten v.减轻，减少(工作量、债务、担忧等); (使) 变明亮，变成淡色; (使)感到不那么悲伤(或担忧、严肃) ; 缓和;
combination n.结合体; 联合体; 混合体; 结合; 联合; 混合; (用于开密码锁的) 数码组合，字码组合;
primary color [词典]原色；基本色；标准色;
secondary color 网络间色; 次生色; 色光二次色; 二次色; 混合色
tertiary color 网络三次色; 第三级颜色; 第三次色; 第三色;
tertiary adj.第三的; 第三位的; 第三级的;
brown n.棕色; 褐色;
grey n.灰色; 烟灰色;
