Light and Color - Detailed Help

Assignment LC8: Filters

Objectives:
• The student should be able to predict the effect which filters have on the appearance (color) of an object of various colors when viewed through the filter.

The Physics Classroom, Light and Color Unit, Lesson 2, Part c

 Suppose that red, green and blue light are incident upon filters of different colors. A red filter can block ____ color(s) of light; a green filter can block ____ color(s) of light; a blue filter can block ____ color(s) of light. Color Subtraction and Filters: A colored filter is a transparent material which transmits (or lets through) light of varying wavelengths (colors). The colors of light which are not transmitted are absorbed or blocked. Many students of physics have seen a diagram similar to the one shown at the right. The diagram depicts three circles colored with the primary colors of light - red, green and blue. The primary colored circles overlap to produce other colors of light, known as the secondary colors of light: cyan (C), magenta (M) and yellow (Y). A filter will absorb or block various colors of light. The color of light which is absorbed or blocked by a particular colored filter is the color directly opposite it on the color wheel. For instance, a yellow filter will absorb or block blue light and allow the other colors of light to pass through. As mentioned in the Dig That Diagram section above, a colored filter will absorb or block its complementary color of light. For instance, a blue filter will block yellow light. However, this question is written in terms of the primary colors of light. So yellow light is actually a combination of the two primary colors red and green (refer to color wheel). So a blue filter will block red and green light. The same logic can be applied to a red and a green filter in order to successfully answer this question.

 Suppose that red, green and blue light are incident upon filters of different colors. A cyan filter can block ____ color(s) of light; a magenta filter can block ____ color(s) of light; a yellow filter can block ____ color(s) of light. Enter the letters of the three choices in their respective order with no commas or spaces between letters. Color Subtraction and Filters: A colored filter is a transparent material which transmits (or lets through) light of varying wavelengths (colors). The colors of light which are not transmitted are absorbed or blocked. Many students of physics have seen a diagram similar to the one shown at the right. The diagram depicts three circles colored with the primary colors of light - red, green and blue. The primary colored circles overlap to produce other colors of light, known as the secondary colors of light: cyan (C), magenta (M) and yellow (Y). A filter will absorb or block various colors of light. The color of light which is absorbed or blocked by a particular colored filter is the color directly opposite it on the color wheel. For instance, a yellow filter will absorb or block blue light and allow the other colors of light to pass through. As mentioned in the Dig That Diagram section above, a colored filter will absorb or block its complementary color of light. For instance, a yellow filter will block blue light. We know this because blue is directly opposite yellow on the color wheel above. The same logic can be applied to a cyan and a magenta filter in order to successfully answer this question.

 Jack is wearing a red shirt. The shirt is illuminated with white light. Jill views Jack's shirt while looking through a magenta filter. To Jill, Jack's shirt will appear ____. (Note: The colors in this question are selected at random and may differ from those listed above.) Color Subtraction and Filters: A colored filter is a transparent material which transmits (or lets through) light of varying wavelengths (colors). The colors of light which are not transmitted are absorbed or blocked. Many students of physics have seen a diagram similar to the one shown at the right. The diagram depicts three circles colored with the primary colors of light - red, green and blue. The primary colored circles overlap to produce other colors of light, known as the secondary colors of light: cyan (C), magenta (M) and yellow (Y). A filter will absorb or block various colors of light. The color of light which is absorbed or blocked by a particular colored filter is the color directly opposite it on the color wheel. For instance, a yellow filter will absorb or block blue light and allow the other colors of light to pass through. Jack's shirt is reflecting light. The color of light which is reflected is the color of his shirt. This light color happens to be a primary light color. Jill is looking at Jack's shirt through a filter. The filter is capable of blocking one or more primary colors of light. You will need to determine if the filter will block the primary color of light reflected by Jack's shirt. Use the color wheel in the Dig That Diagram section above to determine if Jill's filter will block this light color. If Jill's filter does block the light color, then no light will pass through and Jack's shirt will appear black to Jill. On the other hand, if the primary light color is not blocked by Jill's filter, then it will be transmitted to Jill's eyes and will determine the color appearance of Jack's shirt.

 Mac is wearing a magenta shirt. The shirt is illuminated with white light. Tosh views Mac's shirt while looking through a cyan filter. To Tosh, Mac's shirt will appear ____. Color Subtraction and Filters: A colored filter is a transparent material which transmits (or lets through) light of varying wavelengths (colors). The colors of light which are not transmitted are absorbed or blocked. Many students of physics have seen a diagram similar to the one shown at the right. The diagram depicts three circles colored with the primary colors of light - red, green and blue. The primary colored circles overlap to produce other colors of light, known as the secondary colors of light: cyan (C), magenta (M) and yellow (Y). A filter will absorb or block various colors of light. The color of light which is absorbed or blocked by a particular colored filter is the color directly opposite it on the color wheel. For instance, a yellow filter will absorb or block blue light and allow the other colors of light to pass through. Mac's shirt is reflecting light. The color of light which is reflected is the color of his shirt. This light color happens to be a secondary light color. Use the color wheel in the Dig That Diagram section to express this color as a combination of two primary colors of light. Now you know which two primary colors of light are reflected by Mac's shirt and heading towards Tosh's filter. These two primary light colors may or may not be transmitted by the filter. The filter is capable of blocking a single primary light color. Use the color wheel in the Dig That Diagram section above to determine if Jill's filter will block either one of the colors of light. If a color is not blocked, then it passes through and contributes to the color appearance of Mac's shirt. If one of the two colors of light is blocked, then the remaining color is transmitted through the filter and determines the color appearance of Mac's shirt. If neither of the two colors of light is blocked, then both colors are transmitted through the filter and combine together to determine the color appearance of Mac's shirt.

 Ben is wearing a cyan shirt. The shirt is illuminated with white light. Jerry views Ben's shirt while looking through a red filter. To Jerry, Ben's shirt will appear ____. Color Subtraction and Filters: A colored filter is a transparent material which transmits (or lets through) light of varying wavelengths (colors). The colors of light which are not transmitted are absorbed or blocked. Many students of physics have seen a diagram similar to the one shown at the right. The diagram depicts three circles colored with the primary colors of light - red, green and blue. The primary colored circles overlap to produce other colors of light, known as the secondary colors of light: cyan (C), magenta (M) and yellow (Y). A filter will absorb or block various colors of light. The color of light which is absorbed or blocked by a particular colored filter is the color directly opposite it on the color wheel. For instance, a yellow filter will absorb or block blue light and allow the other colors of light to pass through. Ben's shirt is reflecting light. The color of light which is reflected is the color of his shirt. This light color happens to be a secondary light color. Use the color wheel in the Dig That Diagram section to express this color as a combination of two primary colors of light. Now you know which two primary colors of light are reflected by Ben's shirt and heading towards Jerry's filter. These two primary light colors may or may not be transmitted by the filter. The filter is capable of blocking one or more colors of light. Use the color wheel in the Dig That Diagram section above to determine what primary colors of light will be blocked by Jerry's filter. For instance, a red filter will block cyan light (since cyan is directly opposite red on the color wheel). Cyan light is a combination of blue and green light. So if Jerry is using a red filter, then it will not allow neither blue nor green light to pass through. Whichever of the two colors do pass through Jerry's filter will determine the color appearance of the Ben's shirt. If both of the two colors of light pass through the filter, then they will combine together to determine the color appearance of Ben's shirt.