Wavelengths of light

Objective: To learn about the wavelengths of light produced by the sun and the electromagnetic spectrum.

Standards: Objects in the Sky (sky object properties; why is the sun important?), Origin and Evolution of the Universe (how stars produce energy and the formation of all elements), Light, Heat, Electricity, and Magnetism (light reflectance, refraction, and absorption), and Transfer of Energy (light transmission, refraction, absorption, reflection, and scattering; the sun’s range of wavelengths).

Materials: sheet of paper, drinking glass half – filled with water, and a place located outside in full sunlight.

Procedure:

(1) Locate a fully lit outdoor area.

(2) Place the sheet of paper on the ground where you wish to conduct the demo.

(3) Using only your thumb and forefinger, firmly hold the glass of water about three to four inches above the sheet of paper (it is important that you do not
block the sides of the glass while holding it).

(4) Move the glass up and down, while slanting it to focus the light on the paper in a way that a clear, colorful pattern appears.

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Science Behind It: The glass of water serves as a prism in this demo and casts a rainbow of colors on the paper. The glass, as well as other prisms, changes the direction of light by refracting it so that the bands of color can be observed. As the wavelength of light is split and altered by the prism, the many colors that occupy white light become apparent. These properties of light wavelengths and their colors are frequently used by astronomers in determining what elements or gases compose stars. This demo would be a great one to use to introduce the topics of the electromagnetic spectrum, light, or stars.