The Visible Wavelengths of Light

Overview

Objectives/Goals All light sources produce a wavelength or wavelengths of some kind. I performed many experiments to try to study the wavelengths of certain light sources. I thought that the color of the outside of the light source determined what wavelength or wavelengths were produced. Methods/Materials To examine the wavelengths and measure them, I built a spectrometer with a diffraction grating (A device with many grooves that splits the light.) To measure the wavelength I calculated and made a scale using the equation m*lamda=d*sin(theta). The materials used to build the spectrometer were a piece of cardboard 11 inches long by 4 # inches wide, a yardstick, 2 razors, and a diffraction grating, 19,050 grooves per inch. I pointed the slit I had made in my set up and at a lit fluorescent cool white bulb, incandescent light bulb (Frosted White), aquarium light bulb (Clear Glass), black light bulb, and colored bulbs and L.E.Ds (Both yellow and red.) Results My results were that both the incandescent and aquarium bulb had the smoothest spectrum called continuous spectra. The cool white fluorescent light had a continuous spectrum and within the continuous spectrum were two brighter bands, blue and green, called line spectra. The fluorescent full spectrum had line spectra of all the colors. The black light had purple, blue and a dim green line spectrum. With the L.E.D.#s and colored bulbs, I saw a continuous spectrum with the yellow colored bulbs and L.E.D.#s and a small red spectrum with the red colored bulbs and L.E.D.#s. Conclusions/Discussion This concluded that my hypothesis was right when it comes to colored bulbs. However, when it comes to cleared glass aquarium bulbs and frosted white incandescent bulbs, the color of the outside of the bulb did not have any effect on the spectrum and wavelengths produced.

Competition history

• CSEF 2002 Physics & Astronomy · Entry J1535

Resources

• CSEF project summary ↗

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