Investigation 22A: Color, frequency, and wavelength of light

Essential questionsHow is color related to the frequency and wavelength of light?
How are changes in frequency related to changes in wavelength?
What physical property or properties of light make red light different from blue or green light? In this short interactive simulation, you will compare a visible spectrum of light—ranging from violet to red light—with the frequencies and wavelengths of the light.
Part 1: Relating the color of light to its frequency and wavelength

How to use the interactive simulation on the color, frequency, and wavelength of lightIn the interactive simulation, there is a horizontal spectrum of light ranging from violet to red. You can change the light in any of three different ways:
  1. by moving the slider from left to right;
  2. by entering a value in the box for the frequency (e.g., using “6.0 e14” to represent 6.0×1014 Hz); or
  3. by entering a value in the box for the wavelength (in nanometers).
  1. What is the wavelength of blue light? Cyan? Green? Record the wavelengths using scientific notation and correct SI units.
  2. What color of light corresponds to a wavelength of λ = 580 nm?
  3. What color of light corresponds to a frequency of f = 6.9×1014 Hz?
  4. What color(s) of the visible spectrum have the highest frequencies? Longest wavelengths?
  5. Put the following colors in order of increasing frequency: blue, green, indigo, orange, red, violet, and yellow. Can you think of a mnemonic to remember this order of the colors?
  6. How are frequency and wavelength related to each other? In other words, if you change the light to have a longer wavelength, how does the frequency of the light change?
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In this interactive simulation, you will investigate how the color of visible light is related to its frequency and wavelength. Drag the slider to different colors of light, or enter a frequency or wavelength, to explore their interrelationships.
Part 2: Compare to RGB color combinations

What is the wavelength of light for each of these colors?
  1. On page 24, you looked for the best RGB match for each of the colors on the right.
  2. Now using the interactive simulation of the visible light spectrum, look for the best match in the visible light spectrum for each of the colors on the right.
  3. Tabulate the wavelengths you found and describe whether you consider the color to be a good match.
  1. For which colors could you make a good match with the visible light spectrum?
  2. For which colors could you find no suitable match? Explain why this is the case.
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