Which one of the following colours may be obtained by combining green and red colours?
- (a)Blue
- (b)Magenta
- (c)Pink
- (d)Yellow
Correct — D, Yellow. This is additive colour mixing — combining beams of coloured light. Red light and green light added together stimulate the eye's red and green cone cells together, which the brain perceives as yellow. So Red + Green = Yellow is one of the three basic additive results (the others being Red + Blue = Magenta and Green + Blue = Cyan).
- (a)Blue — Blue is itself a primary colour of light; it cannot be produced by mixing red and green — in fact red, green and blue together make white.
- (b)Magenta — Magenta is the additive mix of red and blue light, not red and green.
- (c)Pink — Pink is a pale tint of red (red mixed with white/reduced saturation), not the result of adding green to red light.
Additive colour mixing describes what happens when coloured lights are combined. The three additive primaries are red, green and blue (RGB). Adding pairs gives the secondary colours: red + green = yellow, green + blue = cyan, red + blue = magenta; all three together give white. This is different from mixing paints/pigments, which is subtractive.
The question is about light, so additive rules apply — this is exactly how a TV or phone screen makes yellow, by lighting red and green sub-pixels together with no blue. Candidates who think in terms of paint (where blue + yellow = green) can be misled, so it is essential to spot that the question is about combining colours of light.
- Additive primaries of light are red, green and blue (RGB).
- Red + Green = Yellow; Green + Blue = Cyan; Red + Blue = Magenta.
- Red + Green + Blue light together produce white.
- Screens (TV, phone, monitor) create every colour by mixing red, green and blue sub-pixels additively.
Combining red and green light gives yellow — the pairing asked about in this question.
- Applying paint (subtractive) rules to a question about light (additive).
- Confusing yellow (red + green light) with magenta (red + blue light).
Asked as 'which colour results from combining two given lights' or by naming the additive primaries/secondaries.
No directly related past PYQ was found.
- practice — not a real PYQ
Combining blue and green light produces which colour?
- (a)Yellow
- (b)Cyan
- (c)Magenta
- (d)White
Answer(b) Cyan — green + blue is the additive secondary cyan.
- practice — not a real PYQ
When red, green and blue lights of equal intensity are combined, the result is
- (a)Black
- (b)Yellow
- (c)White
- (d)Magenta
Answer(c) White — all three additive primaries together give white light.