The light shoots into space, and does not enter the eye. The light enters our eye, so we see a red colour.īut the violet light is bent more, and so leaves the drop lower down. In the diagram, red light is refracted on entering the drop, is reflected from the back of the drop, and is bent once more when it leaves. If we follow the paths of two colours inside a raindrop, we can see why. If each raindrop refracts light, why are there bands of colour in a definite pattern in a rainbow instead of a mixture? Once the light is broken into its separate colours, the back of the raindrop reflects the light back into our eyes. Raindrops refract the light in just the way that a prism does, but in the raindrop the water does the refracting. Red light has long wavelengths, so it is bent only slightly. The shorter the wavelength of light, the more it is bent by glass or water. Light travels in waves, and the distance between the crest of two successive waves is called its wavelength. Violet light is bent the most by glass because it has short wavelengths. The order of the colours – red, orange, yellow, green, blue, indigo and violet – is the same as in a rainbow. The colours leave the prism at different points, and make a band of colours. The light is refracted into its separate colours as it comes into the prism. Red light is slowed up least when it enters a substance, and violet light most.Ī raindrop acts like a glass prism, and in the diagram you can see a beam of sunlight entering a prism. The substance shows up coloured light by different amounts, and refracts it.
In air, the colours all travel at 186,000 miles per second.īut in substances such as glass or water, the colours travel at different speeds. The English scientist Sir Isaac Newton was the first man to discover that sunlight is really a mixture of coloured light. When it is reflected, it is bounced back from a surface in the direction from which it came, in the same way that a mirror bounces back your image. When light is refracted it is split up into colours. The raindrops refract or bend the light, and then reflect it back, making a rainbow. Do you know why?Ī rainbow is formed when the sun shines on falling rain. If you ran fast and far enough, could you come to the end of a rainbow? The answer is no. A prism showing the refraction of sunlight into the colours of the rainbow
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