In colour mixing using light (additive colour mixing), what colour is produced when red and green light are mixed in appropriate proportions?

Introduction / Context:
This question explores basic concepts of colour mixing in physics and art, specifically additive colour mixing with light. When coloured lights are combined, the resulting colour depends on how the human eye perceives the mixture of wavelengths. The learner is asked to determine what colour results from mixing red and green light, a fundamental fact often used in discussions about computer screens, televisions, and stage lighting.

Given Data / Assumptions:

• The context is colour mixing of light, not pigments or paints.
• The two primary colours being mixed are red and green.
• The options include light blue, yellow, white, and grey.

Concept / Approach:
In additive colour mixing, which applies to light sources, the primary colours are red, green, and blue. When different combinations of these primaries are mixed, they produce secondary colours and white light. Red and green light together produce yellow light. Blue and green make cyan, red and blue make magenta, and all three together form white. The correct approach is to recall this standard additive colour model and choose the corresponding colour for red plus green.

Step-by-Step Solution:
Step 1: Remember that in additive mixing, red, green, and blue are the three primary colours of light used in devices like televisions and computer displays. Step 2: Recall that when red and green light are combined at appropriate intensities, the human eye perceives the result as yellow. Step 3: Check the options. Light blue would require mixing blue light with either green or red, not just red and green. Step 4: White light is produced by mixing red, green, and blue together at suitable intensities, not simply by combining red and green. Step 5: Grey is not a primary additive mixing result for just two pure colours; it usually indicates reduced intensity or a mix with black. Thus, yellow is the correct result of mixing red and green light.

Verification / Alternative check:
A simple verification is to think of colour wheels and diagrams for additive mixing. Educational charts show red and green overlapping to form yellow in the middle. Another check is to consider pixel structure on digital screens, where each pixel has red, green, and blue subpixels. When the red and green subpixels are activated while the blue is off, the resulting pixel appears yellow. These consistent examples confirm that red plus green equals yellow in additive colour mixing.

Why Other Options Are Wrong:

• Light blue: Typically produced when blue and green are mixed, not red and green.
• White: Requires red, green, and blue all present together at appropriate levels.
• Grey: Not a basic additive mixing outcome of two pure primaries; it often represents desaturated light or shading.

Common Pitfalls:
Many learners confuse additive mixing of light with subtractive mixing of pigments, such as paints. In paint mixing, red and green pigments may produce darker, muddy colours rather than bright yellow. However, in light mixing, the rules are different. To avoid this confusion, remember that additive mixing applies to light sources like screens and stage lighting, where red plus green gives yellow, green plus blue makes cyan, and red plus blue yields magenta.

Final Answer:
When red and green light are mixed in additive colour mixing, the resulting colour is yellow.