FocusSpecial characteristic of

visible light: Color Visible light is the

narrow range of frequencies and wavelengths that can be seen by the human eye

The differences of wavelengths within this range are perceived as differences in color

Objectives Infer where colors come

from Relate color to frequency

and wavelength Explain why objects

appear in a particular color

What I already

know about

light

What I want to

know

What I learned

•What did you see?

• List the colors in order

• How does the acronym ROY G BIV help you describe

what you see?

•Where could have these colors come from?

Objective: In this activity, you should be able to (1) design a color spectrum wheel and (2) explore the special properties of visible light

Procedure: Part 1: Making the Spectrum Wheel Part 2: Characteristics of Light

THz = terahertz = 1012

Nm = nanometer = 10-9

1 hertz = 1 / sec

Q1. Which color registers the highest frequency? shortest wavelength?

Q2. Which color registers the lowest frequency? longest wavelength?

Q3 What pattern do you notice about the wavelength and frequency of the different colors?

Q4. What do you notice about the product of wavelength and frequency for each color? What is the significance of this value?

Q5. What is a possible relationship between wavelength and frequency? What is your basis for saying so?

Q6. What can you say about the speed of the different colors of light in air?

Q7. Give a plausible explanation as to why white light separate into different colors.

Color

Spectrum

Frequency

THz

Wavelength

nmWavelength xFrequency

Red 422 700 m/s

Orange 484 620 8 m/s

Yellow 517 580 3 x 10 8 m/s

Green 566 530 3 x 10 8 m/s

Blue 638 470 3 x 10 8 m/s

Violet 744 400 3 x 10 8 m/s

Q1. Which color registers the highest frequency? shortest wavelength? Violet has the highest frequency and the shortest wavelength

Q2. Which color registers the lowest frequency? longest wavelength? Red has the lowest frequency and the longest wavelength.

Q3 What pattern do you notice about the wavelength and frequency of the different colors?Long wavelength colors have low frequencies.

Q4. What do you notice about the product of wavelength and frequency for each color? What is the significance of this value? The product of wavelength and frequency for each colorare the same. It is very close to the speed of light in air.

Q5. What is a possible relationship between wavelength and frequency? What is your basis for saying so? Wavelength

and frequency are inversely proportional. As the frequency increases wavelength decreases

Q6. What can you say about the speed of the different colors of light in air? The speed of the different colors of light in air are the same.

Q7. Give a plausible explanation as to why white light separate into different colors. Answers may vary.

the visible spectrum consists of color bands and therefore are identified by a range of wavelengths and frequencies to wit

Color Wavelength

λ

nm (10-9 m)

Frequency

THz(1012

Hz

red 780 - 622 384 - 482

orange 622 - 597 482 - 503

yellow 597 - 577 503 - 520

green 577 - 492 520 - 610

blue 492 - 455 610 - 659

violet 455 - 390 659 - 769

Primary colors for light :

RED

GREEN

BLUE

Primary colors for paint pigments

Magenta Yellow cyan

http://users.halpc.org/~clement/Simulations/Mixing%20Colors/rgbColor.html

www.phet.colorado.eduhttp://lrmds.deped.gov.ph

For light For paint pigments

Magenta + yellow = ____

Yellow + cyan = ______

Magenta + cyan = ______

Magneta + cyan + yellow = __________

Q4. Describe the color of the overlap:

Red + blue = ______

Blue + green = ________

Green + red = ________

Red + Green+ Blue = ____

1. Click on the light bulb, paint can, and colored filter icons located in the toolbar on the left side to add them to the lab area. Clicking on an object in the scene removes it from the scene, while clicking on a projector specifies it as the recipient of the next light bulb that is selected. Clicking on the "Animate Beams" button activates the projectors and the user can directly observe how the selected items affect the color of the light beams as they travel through the scene.

http://www.cs.brown.edu/exploratories/freeSoftware/repository/edu/brown/cs/exploratories/applets/combinedColorMixing/combined_color_mixing_java_plugin.html)

Bulb Filter Paint Color we “see”:

Red Red RedGreen BlueMagentaCyanyellow

Green RedGreen BlueMagentaCyanyellow

Blue RedGreen BlueMagentaCyanyellow

White light can be split up to make separate colors. These colors can be added together again.

The primary colors of light are red, blue and green:

Adding blue and red makes magenta (purple)

Adding blue and green makes cyan (light blue)

Adding all three makes white

again

Adding red and green makes yellow

Filters can be used to “block” out different colors of light:

Red Filter

Magenta Filter

The color an object appears depends on the colors of light it reflects.

For example, a red book only reflects red light:

White

light

Only red light is reflected

A white hat would reflect all seven colours:

A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue):

Purple light

White

light

If we look at a coloured object in coloured light we see something different. For example, consider a this pair of shirt and shorts:

White

light

Shorts look blue

Shirt looks red

In different colours of light they would look different:

Red

lightShirt looks red

Shorts look black

Blue

light

Shirt looks black

Shorts look blue

For light:

Primary colors: Red Green Blue

Red+ blue = magenta Blue + green = cyan Red + blue =yellow Red + blue + green =

white

For pigments

The color of a transparent object is the color it transmits

The color of an opaque material is the color it reflects

Evaluate