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Our Surroundings 



light when passing at an angle from one medium into another of 

 different density is bent, or refracted. 



The Spectrum. White light is not a simple color, but is 

 made up of the seven primary colors, all of which have waves 

 of different lengths. Thus when sunlight is passed through a 

 triangular glass prism, the primary colors separate, each being 

 bent a different amount, according to its wave length. The red 

 rays are bent the least, and the violet the most. As a result, 

 the white light is broken up, and in its place we have a band of 

 seven colors red, orange, yellow, green, blue, indigo, and violet 

 which we call the spectrum. 



Violet 

 Red 



How RAINBOWS ARE FORMED 



Raindrops break white light into the spectrum colors. If there is single refraction, 

 as at the left, the seven colors appear in the order commonly seen in the rainbow. 

 If there is double refraction, as at the right, there is a second rainbow whose colors 



are reversed. 



The Rainbow. Everyone is familiar with the rainbow, so 

 often seen in the early forenoon or late afternoon on showery 

 days. It appears when the sun begins to shine through the 

 clouds while the rain is still falling. In order to see the rainbow 

 the observer must stand with his back to the sun, as the rainbow 

 always appears in the opposite side of the heavens from it.- 

 Why? 



