中文说明：在真空中，光以恒定的速度传播；但在介质中，光的速度就要发生变化，并且不同频率的光在同种介质中的传播速度也不相同，这一事实在折射现象中被明显的表现出来，白光通过三棱镜后的色散是众所周知的。它的特点是：白光通过三棱镜后折射为赤，橙，黄，绿，蓝，靛，紫七种颜色的单色光，这七种光在玻璃中的折射率不同，其中，红光最小，紫光最大，由此产生了其中光的分离。
English Description：
In a vacuum, light travels at constant; but in the medium, the speed of light to change, and different frequencies of light propagation speed in the same medium is not the same, the fact that in refraction phenomenon is obviously shown, white light through a prism dispersion is well known. Its characteristics are: white light through a prism refraction is red, orange, yellow, green, blue, indigo, purple seven color monochromatic light, the seven kinds of light in the glass refraction rate different. Among them, red is the smallest, violet maximum, resulting in the light separation.