Sunlight looks white, but a glass prism or a drop of rain shows that it holds many colours. In this course we follow a ray through a prism, we find why white light splits into a spectrum, and we see how raindrops make a rainbow.
3 lessons, about 1 h 15 min3 simulations13 problems6 practice questionsPython in every lesson
Created by StemPy LabA glass prism has two triangular faces and three rectangular faces. A ray that goes through it bends toward the base at both surfaces, and comes out in a different direction. The angle between the incident ray and the emergent ray is the angle of deviation, and i + e = A + deviation.
White light is a mixture of colours. A prism splits it into the seven colours of the spectrum, red, orange, yellow, green, blue, indigo and violet. This is dispersion. It happens because the glass has a different refractive index for each colour, and violet bends more than red. A second prism, turned upside down, joins the colours into white light again.
A rainbow is a natural spectrum. It forms when sunlight is refracted, reflected once inside, and refracted again by raindrops. The Sun must be behind the observer and the rain in front. Red is on the outside of the bow, at about 42 degrees, and violet is on the inside, at about 40 degrees.
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