Which of the following sets of coloured light is/are secondary colours i. Red, Blue and green ii. Blue, cyan…

Analyze the question: We need to find which set(s) contain only secondary colours of light.

Concept:

• Primary colours of light: Red, Green, Blue. They cannot be made by mixing other colours of light.
• Secondary colours of light: Made by mixing two primary colours in equal amounts. • Red + Green = Yellow • Green + Blue = Cyan • Red + Blue = Magenta

Checking each set:

• i. Red, Blue, Green: These are all primary colours, so this set is not correct.
• ii. Blue, Cyan, Magenta: Blue is a primary colour, so this set is not correct.
• iii. Green, Magenta, Yellow: Green is a primary colour, so this set is not correct.
• iv. Yellow, Cyan, Magenta: All three are secondary colours, so this set is correct.

Only set iv is made up entirely of secondary colours.

Answer: C (iv only)

Tip: Remember "RGB" for the primary colours of light. Any colour not in RGB (yellow, cyan, magenta) is a secondary colour. Don't confuse this with pigments, where the primary colours are red, yellow and blue.