Additive and Subtractive Mixing Questions and Answers

Answer: C

Correct answer: reduces its chroma and moves it towards neutral

A complement absorbs where the original reflects, so adding it flattens the reflectance curve and the colour moves towards the neutral axis. It is the standard means of taking the edge off a shade that is too bright - and it costs lightness as well, since more of the spectrum is being absorbed.

Answer: D

Correct answer: True

Neutralising with a complement works by adding absorption in the region the original colourant reflected, so total reflectance falls along with chroma. The result is both duller and darker. Holding the lightness while reducing the chroma requires white or a lighter colourant as well, which is why greying down a shade is a two-part adjustment.

Answer: A

Correct answer: absorbance proportional to concentration at each wavelength

\[ A = \varepsilon c l. \] Beer’s law holds for transparent, non-scattering media, and it is what makes absorbances additive across the components of a mixture. Transmittance and reflectance are exponential in concentration rather than proportional, which is exactly why the transformation to absorbance is made first.

Answer: B

Both are true and the reason gives the mathematics, and this is why absorbance is used. It converts a multiplicative problem into an additive one. Logarithms turn products into sums. Absorbance is the additive quantity.

Answer: C

Correct answer: 1 and 2 only

Statements 1 and 2 give the two additivity results, one for each regime: absorbance for transparent media under Beer’s law, K over S for scattering ones under Kubelka Munk. Statement 3 is what neither transformation would be needed for - reflectance is not additive in either case, and assuming otherwise is the fundamental error in colourant mixing.

Answer: D

Correct answer: two transparent filters placed one behind the other

Stacked filters each remove part of the spectrum from the same beam, which is subtractive. The other three all add light on the retina: two beams superimposed, sectors alternating faster than the eye can follow, and dots too fine to resolve - the last two being temporal and spatial additive mixing respectively.

Answer: A

Correct answer: subtractive, since each removes part of the spectrum

The light must pass through both filters, so what emerges is what neither absorbed - the transmittances multiply. A cyan and a yellow filter together pass only green, and cyan with magenta and yellow together pass almost nothing. Superimposing the beams of two coloured lamps would be the additive case.

Answer: B

Each transmits where the other absorbs, so almost nothing survives both. This is a direct demonstration of the multiplicative nature of filtering. Each transmits where the other absorbs. Almost nothing survives both filters.

Answer: C

Expecting red and green paint to give yellow is the familiar instance. The two processes obey different rules and produce different results. Red and green paint gives brown, not yellow. The two processes must not be confused.

Answer: D

Overlapping lights add their spectra rather than removing wavelengths. The other three each remove part of the spectrum successively. Overlapping lights add their spectra instead. Only the first three remove wavelengths.