A mixture of blue and red pigment when illuminated by white light will appear

Analysis of the Question

This question tests your understanding of color addition and subtraction in the context of pigments (subtractive color mixing) versus light (additive color mixing). We are looking at what happens when pigments are mixed and then illuminated by white light.

Concept Explanation

1. Pigments (Subtractive Mixing): Pigments work by absorbing specific wavelengths of light and reflecting others. When you mix pigments, you are essentially combining their absorption properties.
2. Red Pigment: Absorbs all colors except red (it reflects red).
3. Blue Pigment: Absorbs all colors except blue (it reflects blue).
4. The Mixture: When you mix red and blue pigments, the resulting mixture absorbs almost all colors of the visible spectrum except for the red and blue light that the individual pigments reflect.
5. Perception: When white light (which contains all colors) hits this mixture, the red pigment absorbs the non-red colors, and the blue pigment absorbs the non-blue colors. The light that is reflected to your eyes is a combination of red and blue light. In the context of color theory, the combination of red and blue light is perceived as magenta.

Step-by-Step Solution

• Step 1: Identify the nature of the pigments. Red pigment reflects red light; blue pigment reflects blue light.
• Step 2: Determine the effect of mixing. Mixing pigments is a subtractive process. The mixture will reflect the colors that neither pigment absorbs.
• Step 3: Combine the reflected colors. The mixture reflects both red and blue light.
• Step 4: Identify the resulting color. According to the principles of color mixing, the combination of red and blue light is magenta.

Conclusion

When white light hits a mixture of red and blue pigments, the red and blue light are reflected back to the observer, while other colors are absorbed. This combination is perceived as magenta.

Exam Tip

Remember the difference between Light (Additive) and Pigments (Subtractive):

• Light: Red + Green + Blue = White.
• Pigments: Mixing primary pigments (Cyan, Magenta, Yellow) creates black.
• For simple pigment mixing questions, think of the primary colors of light: Red + Blue = Magenta.