The Colors of Light

Jackie Johnson

Educ 373

Standard Indicator 6.3.21

Investigate, using a prism for example, that light is made up of a mixture of many

different colors of light, even though the light is perceived as almost white.

http://www.indianastandardsresources.org/files/sci/sci_6_3_21.pdf

Terms to know…

• Prism - a transparent solid body, often having triangular bases, used for dispersing light into a spectrum or for reflecting rays of light

• Wavelength - the distance between one peak or crest of a wave of light, heat, or other energy and the next corresponding peak or crest

Background Information

• “White light” contains all colors of light• The light we see passing through a prism is the refracted

(bent) white light and inside the prism we should see all of the colors of light

• The light seen in the prism is a separation of the white light because of the refraction in the prism

• Isaac Newton was the first person to discover that a prism refracted light and he proved that “white light” was made of many different colors of light

• We see rainbows when it rains because the tiny rain droplets act as small prisms, creating the bent wavelengths of the different colors of the rainbow

• Different wavelengths create the different colors

Time to explore!

• Using the prism, stand near a window on a sunny day.

• Hold the prism up to the sunlight and observe the light that comes out of prism as the white light passes through. What does this look like? (Be sure to not look directly into the sun!)

• Move the prism around slightly until you are able to see a rainbow of colors coming from the prism.

What was happening?

• Move the prism around until you were able to see all of these colors:

• These are all of the colors that make up white light.

RED ORANGE YELLOW GREEN BLUE PURPLE

You don’t believe 6 colors can make “white light”? Let’s prove it!

• With the white paper given, cut a disk with a diameter of 10cm.

• Divide the disk into 6 equal sections using your protractor. (Hint: 360° divided by 6 is 60° sections, or fold your disk into 6 equal sections)

• Color each of the sections the colors of the spectrum (Hint: ROY G. BIV knows the colors!)

Creating White Light

• Make a small hole in the middle of your tip if your sharpened pencil.

• Leave the pencil in the hole and spin the disk quickly on the pencil.

• You should see a grayish/white color…you just created white light!

Why could you not see the colors?

• When the disk you created was spun quickly, your eyes were not able to see each color separately because it was moving.

• The grayish/white color you saw was simply a mixing of all of the colors, just as we do not necessarily see the colors from the sunlight.

References

• http://www.indianastandardsresources.org/files/sci/sci_6_3_21.pdf

• www.dictionary.com

• http://www.light-science.com/lightprism.html

• http://eo.ucar.edu/rainbows/

• http://www.cs.dartmouth.edu/farid/sciencekids/rainbow.html