White Light

1

• White Light
• The combination of all the colors. Sunlight is
  an example of white light.
• Newton showed that the colors in the spectrum
  were a property not of the prism, but of white
  light.

2

• Newton was the first to show that sunlight is a
  mixture of all the colors by splitting the light
  into different colors through a spectrum.
• He also noted that they always formed the colors
  in a particular order.
• Red Yellow Orange Green Blue Indigo Violet
• ROY G BIV

3

• Just as white light is a combination of all the
  colors, black is the absence of light. So,
  essentially it is not really a color at all.
• Objects appear black when they absorb all visible
  frequencies of light.

4

• When we see colors, we are seeing the absorption
  and reflection of light.
• If we look at a flower, frequencies of light are
  absorbed and reflected. The leaves contain
  chlorophyll and absorb all the colors except
  green. Green light is reflected. A red rose
  reflects mostly red light.
• Not all objects reflect only one color.
  Daffodils, for example, reflect red, yellow, and
  green frequencies, but not blue.

5

• The appearance of the color of objects depends on
  the kind of light reflection off them.
• Candle light is deficient in the blue frequency,
  so things appear more yellowish in candle light.
• Fluorescent light is rich in higher frequencies
  so things have a more bluish quality to them.
• If picking out fabric, the color will appear
  different in the store versus outside in the
  sunlight.

6

• Q1 When red light shines on a red rose, why do
  the leaves become warmer than the petals?
• Q2 When green light shines on a red rose, why
  do the petals look black?
• Q3 What color does a daffodil appear when
  illuminated with red light? With yellow light?
  With blue light?

7

• In the visible light spectrum, the brightness of
  the light varies.
• The yellow to green section emits the brightest
  light.
• The blue to violet light emits the lowest
  brightness.
• Red to orange is in the middle of the brightness.
• See the graph on page 404 of the text.

8

• Back to Kindergarten
• The primary colors are red, blue, yellow, right?
• And red and blue make purple.
• And red and Yellow make orange
• And blue and yellow make green
• Not so with light.

9

• The primary colors seem to be red, green, and
  blue. The reason is because they are from the
  ends and middle of the visible light spectrum.
  So,
• Red and Green make Yellow, because the lower and
  middle frequencies combined make yellow.
• Green and Blue make Cyan, because the middle and
  higher frequencies combined.
• Red and Blue make Magenta

10

• Red, Green, and Blue are primary light colors,
  Yellow, Cyan, and Magenta are secondary colors.
• Mixing red, green, and blue together makes white
  light.
• Complementary colors are when two colors combine
  to produce white light.
• Blue and yellow make white light.
• Green and magenta make white light.
• Red and cyan make white light.

11

• Q1 What are the complementary colors of a)
  magenta, b) blue, and c) cyan?
• Q2 - What color does red light pluse blue light
  appear?
• Q3 What color does white light minus yellow
  light appear?
• Q4 What color does white light minus green
  light appear?