PHET SIMULATION on “LIGHT & COLOR” Name ______Access: Google “PhET simulations.” Light & Radiation. Launch the Color Vision Simulation. “Run Now.”
General: Play with the simulation for a few minutes. (Not more than 5).
1) What do you think the moving, colored dots represent?______
2) What do you think the colored cloud above the man’s head represents?______
______
PART I: Color Addition: Use the RGB Bulbs Tab
3) Each light has a color gradient. For the best results, slide the bar to the very top of each color. Each color should be observed individually for this first part. To stop the color, return the bar to the black location.
a) What color is seen when the red light is on?______
b) What color is seen when the green light is on?______
c) What color is seen when the blue light is on?______
4). Now you will investigate the effects of mixing two colors. Before you begin each part,
***be sure to make a Prediction.
a) What color do you think the man will see when red and green are mixed together?______
b) Turn on the red and green, both to the very top of the color scale. What color does the manactually see?
______
c) Experiment with the degree of color. While doing this, make sure that both colors are inequal locations on the
scale. What colors do you observe?______
______
d) Do you they still fit into the same color family as the color observed in “b’? Why or why not?______
______
5) Keep the red light on (to the top red location), and turn off the green. You will be looking at red andblue next.
a) What color do you think the man will see when red and blue are mixed together?______
b) Turn on the red and blue, both to the very top of the color scale. What does the man actually see?______
______
c) Experiment with the degree of color. While doing this, make sure that both colors are in equal locations on the
scale. What colors are observed? ______
______ d) Do you they still fit into the same color family as the color observed in ‘b’? Why or why not? ______
______ 4) Keep the blue light on (to the top blue location), and turn off the red. You will be looking at green and blue next.
a) What color do you think the man will see when green and blue are mixed together?______
b) Turn on the green and blue, both to the very top of the color scale. What does the manactually see?______
c) Experiment with the degree of color. While doing this, make sure that both colors are in equal locations on the
scale. What colors are observed? ______
d) Do you they still fit into the same color family as the color observed in ‘b’? Why or why not? ______
______
4)Now you will be looking at mixing “all three colors.”
a) What color do you think the man will see when red, green and blue are all mixed together?______
b). Turn on all three colors, all to the very top of the color scale. What does the man actually see?______
______
c). Fill in the color diagram below. Provide the appropriate colors that you observed when each was mixed. Use
colored pencils or crayons.
PART II: More on Color Addition
Red, green, and blue are commonly referred to as the primary additive colors and are used in TV screens and computer monitors. Addition of varying amounts of these primary additive colors generate the enormous variety of colors that can be displayed. You can see these primary colors by placing small lenses on the screen (i.e. Sprinkle a few small drops of water on the screen). Please do not spit on t he screens. I have a little water for you to use!
5). Why do you think you can see the individual wavelengthsof light as colors? Whatmust happen to the light
wavelengths of light when they enter thisnew medium? Hint: Look on page 585 in your textbook…Don’t guess!______
6)Try to mix the color brown. Approximately what ratio/percentageof each color did you use?
Red ______Green ______Blue ______
7)Try to mix the color purple. Approximately what ratio/percentage of each color did you use?
Red ______Green ______Blue ______
8)Try to mix the color orange. Approximately what ratio/percentage of each color did you use?
Red ______Green ______Blue ______
PART III – COLOR SUBTRACTION - Use the Single Bulb Tab
In elementary art, you learned about mixing pigments. The primary subtractive pigments are cyan, magenta, and yellow. These are exactly the colors you find by mixing any two primary additive colors of light at full intensity. These colors still do not quite match your elementary school education; however, how many first graders know about cyan and magenta? You are, nevertheless, quite familiar with these colors as they are used as pigmentsin every color ink jet printer to produce photo quality color images. Pigments produce colors by removing select wavelengths of light from the light beam.
1)Set the simulation to the following: bulb type – ‘white,’beam – ‘photons,’ and filter color – ‘off’.’
a) What is coming out of the bulb?______
b) What color light does the man see?______
2)Set the simulation to the following: bulb type – ‘white’, beam – ‘solid’, and filter color – ‘off’.
a) What is coming out of the bulb?______
b) What color light does the man see?______
3)Select a yellow filter and a monochromatic bulb type of yellow.
a) What is coming out of the bulb before the filter (in the area just in front of the filter)?______
______
b) What is coming out after the filter?______
c) What color light does the man see?______
d). Using the words “absorb” and “transmit,” explain why the man perceives yellow. ______
______
______
4)Before making any more changes,hypothesize what might happen if the filter is changed to red.______
______
a). Do the experiment. Is your hypothesis supported? ______If not, revise your hypothesis.
b). Return both your light and filter to yellow. Hypothesize what might happen if the filter ifchanged to
blue. ______
______
c). Do the experiment. Is your hypothesis supported? ______If not, revise your hypothesis.
d). Return both your light and filter to yellow. Hypothesize what might happen if the filter ifchanged to
light orange.______
______
e). Do the experiment. Is your hypothesis supported? ______If not, revise your hypothesis.
f). Generalize your hypothesis. In other words, what will happen when the filter and bulb colors are nearly the
same? ______
______
5) Select a bulb color and a filter color that are different. Record the colors chosen below. What does the man see?
Bulb Color: ______Filter Color:______Color seen by the man:______
6) Select a bulb color and a filter color that are the same. Record the colors chosen below. What does the mansee?
Bulb Color: ______Filter Color:______Color seen by the man:______
7) What is the filter doing?______
______
PART IV PHET SIMULATION: “INTERACTIONS of LIGHT: Reflection, Diffraction, and Interference”
DIRECTIONS: Access: Google “PhET simulations -Wave Interference”
Directions: Next Click on “Wave Interference” simulator and click “Run Now.” Open the “Light” tab. Click on the “+” sign in the top right corner to enlarge the screen.. Launch the Wave InterferenceSimulation. “Run Now.”
General: Play with the simulation for a few minutes. (Not more than 5).
A. Light Wave Simulator
- Click “show graph.” What happens when you vary the amplitude? What happens if you put the amplitude at 0?
- What happens to the wavelength and frequency as you change the color from violet to red? What can you say about the difference in colors?
- Now add a slit. Vary the width of the slit. What is the relationship between the bending of a light wave(called diffraction) and the size of the opening?
- Move the slit back and forth. What happens to the wave as the slit gets closer and farther from the source?
- How does changing the color affect this?
6. Try putting two light sources togetherand describe what you see. Why do you think this happens?
- When two waves overlap, interference occurs. Sketch the interference pattern shown on the screen for “one-light-two
slits”. What do you think the light areas represent? The dark areas?
8. Click “Reset.” Add a mirror. Vary the angle of the mirror. Sketch and describe the wave interaction that occurs.