Purpose: to Investigate How the Color of Light Help Us Understand the Matter

Spectra Activity

Answer Key

Activity 1

Purpose: to investigate how the color of light help us understand the matter

Material: flashlight and packet of gel color filters

Procedure: it is important to make careful observations during each step of the investigation.

While the overhead light is on, shine a flashlight on a white paper. Explain why the paper looks brighter when a flashlight is shining on it. (Possible Answer: The addition of the overhead light and the flashlight made the paper look brighter. There is more light reflecting back to my eyes when both light sources are on. This is evidence that brighter light is made when light from various sources is added together.)

Predict what color of light you will see on the paper when you aim three flashlights covered with red, green and blue gel filter so that their circles are overlapping. Prediction:______

Join with other groups to share flashlights and try it. What color do you see? ______Explain why you saw the color you did when all three colors of light were overlapping.

(Possible Answer: White. Red, blue and green are the primary colors of light. When all the colors of light are added together, the light is the brightest it can be and reflects white light to my eyes. This is evidence that white light is composed of red, green and blue.)

Now what do you see on the paper when a red filter is placed on the flashlight?______Why do you see this color?(Possible Answer: The white paper has a red circle of light on it. There is red light reflecting back to my eyes. This is evidence that some parts of the white light from the flashlight are absorbed by the red filter. The colors that must be absorbed are the blue and the green since we know the light from the flashlight is white.)

Team up with another group. Try mixing the light of red and green colors of gel filter over two flashlights. Is the new color you see is brighter than the original colors you mixed? Explain why this happens. (Possible Answer: Yes, the color from two flashlights shining on the same spot will be brighter no matter what 2 color filters are chosen. When more light is added together, the brighter the light will be. Also, the combined light is yellow. This shows that combining light is different than combining pigments.)

Activity 2

Purpose: to investigate color in light

Material: flashlight, packet of gel color filters and a piece of C-Spectra or a spectroscope for each student.

Procedure:

Look through the C-spectra toward a white light of the flashlight. Make a list of the colors that you see.(Possible Answer: Red, orange, yellow, green, blue, indigo and violet – ROY G BIV) ______

Predict what you will see if you cover the flashlight with a yellow filter and then look toward the yellow light using the piece of C-Spectra. Predicted colors:______Now do it and observe carefully. What colors do you see?______(Possible Answer: dull red, orange and yellow.)

What happens to the other colors of light when it goes through a yellow colored filter?(Possible Answer: When the yellow filter is added, the blue and violet colors disappear. These colors are absorbed by the yellow filter. The yellow and orange light is transmitted without any change. It is important for to students to know that the missing colors were absorbed by the filter.)

Activity 3

Purpose: to investigate other filters of light

Material: C-spectra, colored pencils, markers or crayons.

The continuous spectrum below occurs when all light wavelengths are displayed.

Image from

Procedure: After the gas tube is connected to the power supply, look at the tube through the C-spectra film.As you look at the light transmitted from each gas, draw each color line that you see in the box.Instead of coloring the black you see, just leave it white.

This pattern of light is the emission spectrum of the gas you are viewing.

Emission Spectrum of Gas 1:_H- Hydrogen_

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 2:__He - Helium__

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 3:___Ne- Neon_

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 4:__Hg - Mercury__

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Answers: Sodium is not available in a gas tube. A flame test will reveal the sodium emission spectrum.

Imagesof spectra are available from the

Questions:

What did you learn about gases when you looked at them through the C-spectra film?

(Possible answer: Each gas showed different colors. Each gas was unique and had a unique fingerprint as shown in its emission spectrum.)

Could you tell what an unknown gas is if you know its color pattern? After observing the emission spectra of the gases, name the gas whose emission spectrum is shown below. (Answer: hydrogen)

What do you know about the property of elements that could explain your observations? (Possible Answer: Each element on the periodic tables has properties that are unique to that element. Each element has different number of protons and electrons which make the element different from any other element.)

Spectra Activity

Activity 1

Purpose: to investigate how the color of light help us understand the matter

Material: flashlight and packet of gel color filters

Procedure: it is important to make careful observations during each step of the investigation.

While the overhead light is on, shine a flashlight on a white paper. Explain why the paper looks brighter when a flashlight is shining on it.

Predict what color of light you will see on the paper when you aim three flashlights covered with red, green and blue gel filter so that their circles are overlapping. Prediction:______

Join with other groups to share flashlights and try it. What color do you see? ______Explain why you saw the color you did when all three colors of light were overlapping.

Now what do you see on the paper when a red filter is placed on the flashlight? ______Why do you see this color?

Team up with another group. Try mixing the light of red and green colors of gel filter over two flashlights. Is the new color you see is brighter than the original colors you mixed? Explain why this happens.

Activity 2

Purpose: to investigate color in light

Material: flashlight, packet of gel color filters and a piece of C-Spectra or a spectroscope for each student.

Procedure:

Look through the C-spectra toward a white light of the flashlight. Make a list of the colors that you see. ______

Predict what you will see if you cover the flashlight with a yellow filter and then look toward the yellow light using the piece of C-Spectra. Predicted colors:______

Now do it and observe carefully. What colors do you see?______

What happens to light when it goes through a colored filter?

Activity 3

Purpose: to investigate other filters of light

Material: C-spectra, colored pencils, markers or crayons.

The continuous spectrum below occurs when all light wavelengths are displayed.

Image from

Procedure: After the gas tube is connected to the power supply, look at the tube through the C-spectra film.As you look at the light transmitted from each gas, draw each color that you see in the box. Instead of coloring the black you see, just leave it white.

This pattern of light is the emission spectrum of the gas you are viewing.

Emission Spectrum of Gas 1 :______

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 2:______

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 3:______

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Emission Spectrum of Gas 4:______

700 nm600nm500 nm400 nm Wavelength

RedOrange Yellow Green Blue Indigo Violet Color

Questions:

What did you learn about gases when you looked at them through the C-spectra film?

______

Could you tell what an unknown gas is if you know its color pattern? After observing the emission spectra of the gases, name the gas whose emission spectrum is shown below.

What do you know about the property of elements that could explain your observations?

______