Light and Color

Physical Science - Middle School

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Light & Color Color for Opaque Objects Why does an apple look red and a leaf green? When white light strikes the surface of the apple, only red light is reflected. All the other colors are absorbed . Your eyes only see the red light, so you say the apple is red. The leaf appears green because only green light is reflected from the leaf. White objects reflect all the colors of light. Black objects absorb all the colors of light. A black t-shirt gets hot in the Sun because the black material absorbs all the energy of the light which is converted to heat . Transparent or Translucent Objects A color filter is a transparent or translucent material such as the lenses of your sunglasses. An object can appear to be a different color than it actually is if it is viewed through a color filter. For example, a red apple normally appears red because it reflects red light. However, when this red apple is viewed through a green filter , the red light is absorbed and the red apple will now appear black. Its green leaf will still look green because the green light can pass through the lens. red green blue magenta yellow cyan white Additive Color System Subtractive Color System white light yellow cyan magenta yellow cyan magenta red green blue black red green blue magenta yellow cyan white Colors of Pigments The primary colors of pigments are magenta , yellow , and cyan . Any of these two primary pigments can be combined to produce a secondary pigment color. For example, magenta and cyan when combined make blue. However, when the three primary colors are combined in equal amounts, all the colors of light are absorbed resulting in a black pigment. The colors you see on a printed image are produced by combining different color pigments . secondary colors primary colors primary colors secondary colors Visible Light Your eyes are tuned to see a very small portion of the electromagnetic spectrum which scientists call visible light. Visible light waves have wavelengths in the range of 400 nm to 700 nm. These wavelengths are seen by humans as different colors. The longest wavelength, 700 nm, is seen as red light, while the shortest wavelength of 400 nm is seen as violet light. This range of colors which humans can see is called the visible spectrum. 1 2 3 4 5 6 7 8 9 0 1 + - - + 2 3 4 5 6 7 8 9 0 radio radio waves waves microwaves X-rays ultraviolet infrared infrare gamma rays 9 8 0 7 9 8 7 6 5 4 3 2 1 2:13 3 2 78 9 0 + + + - - + 1 2 3 4 5 6 7 8 9 0 700 nm red light 400 nm violet light white light color light dispersion Visible Light © Copyright NewPath Learning. All Rights Reserved. 94-4479 Visit www.newpathlearning.com for Online Learning Resources. Combining Colors of Light Primary colors of light blue , green and red combine to produce white light . Secondary colors of light are produced by combining two different primary colors known as color addition . For example, red and blue combine to produce magenta , red and green produce yellow , while green and blue produce cyan . The colors that you see on your television or computer are produced by color addition . yellow cyan magenta yellow cyan magenta red green blue black
Light & Color 1) What are the three primary colors of pigments? ___________________________________________________________________ 3) What are the three primary colors of light? ___________________________________________________________________ 2) What is the result of mixing three primary colors of pigments? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ 4) What is the result of mixing three primary colors of light? ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ 5) Explain why an apple looks red. ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ ___________________________________________________________________ Pause and Review Answer the questions below. © Copyright NewPath Learning. All Rights Reserved. 94-4479 Visit www.newpathlearning.com for Online Learning Resources.