2a) If I were in a photography darkroom with a red light while wearing a green shirt, my shirt would look black. This is because the green shirt absorbs the red light and does not reflect it. This causes the shirt to appear black because the green is not reflecting off of the light. Without a reflection and only absorption, an object will appear black.
2b) Because a light yellow is closer than a darker yellow to white, then all colors will filter through. A darker yellow, however, will limit the amount of light to filter through. This causes colors such as violet, indigo, blue, and green to not filter through the darker yellow.
2c) The 3D effect works in that the same picture is taken with two different lenses: one with a blue lens, the other with a red. These two pictures are then added to the original image. The red light will pass through the red lens of the 3D glasses, and the blue filter will let blue light through the blue lens. Your brain then combines the two images to create the 3D effect.
