Question

When green and red colours are mixed, the colour produced is:
A) Yellow
B) Magenta
C) Indigo
D) Black

Answer 1

Hint: The three primary colours are red, blue and green. The four secondary colours are violet, indigo, yellow and orange. All the other colours are known as tertiary colours.

Completely answer:
Red, Blue and Green colours are known as primary colours. Because all the other colours in the world can be made from these letters directly or indirectly. Secondary colours are colours which are made up of primary colours directly. Tertiary colours are made up with the help of both primary and secondary colours.
Visibility of colours is possible because of different wavelengths of different colours. When the wavelengths of any two primary colours is mixed, the resultant wavelength produces the resultant colour.
$\Rightarrow \dfrac{1}{{{\lambda _{net}}}} = \dfrac{1}{{{\lambda _1}}} + \dfrac{1}{{{\lambda _2}}}$
Since magenta is a tertiary colour and cannot be made up from two primary colours.
Hence, option B is not the correct answer.
Black is a colour that is devoid of all the colours. Which means that to obtain black colour in an object, that object needs to absorb all the colours and should not reflect any colour back. When no colour enters our eye, we see black colour. Hence, option D is also not a correct answer.
Indigo is a colour whose wavelength is shorter than both, red and green and that’s why it cannot be made from the two. Hence, option C is also not the correct answer.
Yellow colour is a colour which falls between red and green and that’s why option A is the correct answer.

Note: Whatever we see because of the light that gets reflected and enters our human eyes. Even the colors. For every color there is a specific wavelength. The red and green colors have different wavelengths as well. But when they are mixed their mixture has a different wavelength.