Q 01/05

In the mnemonic ROYGBIV for the colours of the rainbow, what does the I stand for?

A) Indigo

B) Ice blue

C) Ivory

D) Iris

Answer · why

A) Indigo

Indigo: Isaac Newton spelled it 'indico', and it was one of two colours he added to his original five.

Q 02/05

Isaac Newton gave the rainbow seven colours rather than five to match what?

A) Seven liberal arts

B) Seven virtues

C) Seven notes of a major scale

D) Seven wonders of the world

Answer · why

C) Seven notes of a major scale

Seven notes of a major scale: yet Newton admitted that his own eyes were not very good at telling colours apart.

Q 03/05

Which astronomer discovered infrared radiation in 1800 by testing a spectrum's colours with thermometers?

A) Charles Messier

B) William Herschel

C) Pierre-Simon Laplace

D) Edmond Halley

Answer · why

B) William Herschel

William Herschel: the warmest reading of all came from just beyond the red end of the spectrum, where no light could be seen.

Q 04/05

The daytime sky looks blue mainly because of which physical effect?

A) Compton scattering

B) Doppler shift

C) Bragg diffraction

D) Rayleigh scattering

Answer · why

D) Rayleigh scattering

Rayleigh scattering: air scatters the short blue waves of sunlight far more than longer red ones, so blue light reaches our eyes from all over the sky...

Q 05/05

In the CMYK printing model, what does the K stand for?

A) Kobalt

B) Kelvin

C) Key

D) Kohl

Answer · why

C) Key

Key: black can be mixed from cyan, magenta and yellow inks, but printers usually add black ink instead for crisper text and less ink.