Students at Saltonstall were very busy this week exploring the nature of LIGHT. Light is a form of energy that travels in waves, and different types of light have characteristic wavelengths. We see different wavelengths of visible light as colors! You may remember the mnemonic “ROY G BIV”, which helps remind people the order of colors in the rainbow. We also call those colors of light visible light because they are the wavelengths that we can see. The sun emits a wide range of light outside of the visible spectrum, including microwaves and ultraviolet light, which many other animals can see.
The students modeled a light wave using a rope, and learned that short wavelength, high frequency, and high energy all go together. A series of activity stations helped reinforce their understanding of reflection and refraction, the differences between transparent, translucent, and opaque objects, and why and how we perceive different colors. We examined the way light interacts with materials and the terms absorption and transmission were introduced, with examples of materials illustrating each property. The students were also very interested in our experiments dealing with the effects of refraction (the bending of light as it passes from one material to another). While examining a glass that was partially filled with water, that also had a pencil in it, students noticed that from some angles the light reflected off of the surface of the water, while at other angles they were able to see through it. Students also noted that at the interface of the water and air the pencil looked as if it was cut into two separate pieces.
Their favorite station involved exploring color mixing. By looking at colored CD disks while they spin the students got to experience how colors of light mix together to produce new colors compared to mixing colored pigments such as paint.
To examine the different light spectra produced by different light sources (incandescent vs. fluorescent bulbs, LEDs, and sunlight) make a spectrometer at home using this link: http://orbitingfrog.com/2008/07/02/make-your-own-spectrometer/
Two notes: 1) use folded aluminum foil instead of razor blades for the slit, 2) It’s helpful to score the CD with a blade (a job for parents) before breaking it, and to cover it with a towel while you snap it, to keep pieces from scattering. Once broken, the CD pieces are easy to trim with a scissors.