Additive and Subtractive Mixing Questions and Answers

Answer: A

The spectra add, so the mixture is always lighter than either component alone. Displays and stage lighting are the familiar examples of the process. The spectra add rather than being removed. A mixture is always lighter than its parts.

Answer: B

Correct answer: A-2, B-4, C-1, D-3

Additive mixing works with light, so its primaries are red, green and blue, and a display realises them as emitting elements. Subtractive mixing works with colourants that remove light, so its primaries are cyan, magenta and yellow, and printing adds black to the three for the reasons of depth, ink coverage and text definition.

Answer: C

Red and green lights together stimulate the L and M cones much as yellow light does. Mixing red and green paint gives a dull brown instead, since that is a subtractive process. The two processes obey quite different rules.

Answer: D

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the mechanism. Red and green lights add their power together and the sum stimulates the eye as yellow does. Red and green paints each absorb most of what the other reflects, so what survives both is a small amount of light across the middle of the spectrum - a dull brown.

Answer: A

The first two are correct and follow from the physics. The third is wrong, since one adds spectral power and the other removes it. Lightness moves opposite ways in the two cases. One adds power and the other takes it away.

Answer: B

Each colourant absorbs certain wavelengths, so what remains is progressively reduced. The result is always darker than either colourant taken alone. Each colourant removes part of what remains. The result is darker than either component.

Answer: C

Each subtractive primary removes one of the additive primaries from the light. This complementary relationship is the whole basis of the system. Each subtractive primary is minus one additive one. The two sets fit together exactly.

Answer: D

Its reflectance is high in the green and blue and low in the red. Magenta and yellow are minus green and minus blue by the same reasoning. Each reflects two thirds of the spectrum. Naming them minus red and so on is exact.

Answer: A

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the mechanism. Cyan absorbs the red third of the spectrum and passes green and blue; magenta absorbs green; yellow absorbs blue. Each subtractive primary is therefore white light minus one additive primary, which is why the two sets of three are complementary rather than unrelated.

Answer: B

In practice the result is a muddy dark brown rather than a true black. Real inks are not ideal absorbers, which is why a separate black is added in printing. Ideal absorbers do not exist in practice. A fourth ink is added for that reason.