A. Light filters work by absorbing certain wavelengths of light and transmitting others. When white light, which contains all colors, passes through a colored filter, only the color of light that corresponds to the filter is allowed to pass through, while other colors are absorbed.
For example:
- A red filter allows red wavelengths to pass through and absorbs green and blue wavelengths.
- A green filter allows green wavelengths to pass through and absorbs red and blue wavelengths.
- A blue filter allows blue wavelengths to pass through and absorbs red and green wavelengths.
When white light passes through a colored filter:
- If white light goes through a red filter, the light that emerges is red.
- If white light goes through a green filter, the light that emerges is green.
- If white light goes through a blue filter, the light that emerges is blue.
B. When combining colored light, the resulting color perceived by a person depends on the combination of light transmitted through different filters. Here’s a breakdown of what happens with various combinations of red, green, and blue light:
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Red light + Green light = Yellow light: The combination of red and green light creates yellow.
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Red light + Blue light = Magenta light: The combination of red and blue light creates magenta.
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Green light + Blue light = Cyan light: The combination of green and blue light creates cyan.
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Red + Green + Blue light = White light: When all three colors are combined, the result is white light.
When using filters, the following outcomes are observed based on the combinations of filters:
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Red filter and green filter: If red light passes through a red filter, it remains red. If green light passes through a green filter, it remains green. Therefore, a person sees no light (darkness) if the filters are used together, as both red and green light are being selectively filtered out.
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Red filter and blue filter: If red light passes through a red filter, it remains red, and if blue light passes through a blue filter, it remains blue. The observer will see red if only looking through the red filter, or blue through the blue filter, but when combined, they will see no light.
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Green filter and blue filter: If green light passes through a green filter, it remains green; if blue light passes through a blue filter, it remains blue. The observer will see green through the green filter, blue through the blue filter, and again, if both are used together without their respective colors being presented, they will see no light.
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If red, green, and blue light are all combined/allowed to pass through, the observer will see white light.
Understanding light filtering and color combinations requires recognizing how the three primary colors of light (red, green, and blue) interact to create different visual outcomes.