Rainbow is an optical and meteorological phenomenon in the form of colorful light parallel to each other in the sky or other medium. In the sky, the rainbow appears as an arc light with the tip leads to the horizon at a moment of light rain.

Sunlight is polychromatic light (comprised of many colors). The white color of sunlight is actually a combination of various light with a wavelength different. The human eye is capable of perceiving at least seven colors contained in sunlight, which will look at the rainbow: red, orange, yellow, green, blue, indigo, and violet.

Isaac Newton was the first to investigate why the white light can produce a spectrum of rainbow colors. Newton conducted experiments to investigate this matter. sunlight is directed at a narrow hole in a dark room. if a glass prism is placed such that the sun will be seen as a spectrum of colors.

Rainbow occurs because of the refraction of light. Light passing through two different mediums will undergo refraction and change its direction. The wavelength of light forming tape parallel lines, each color shades of the color next to it. This tape is called a spectrum of colors. In the spectrum of colors, the red line is always located on one side and blue and purple on the other hand, and this is determined by the difference in wavelength.