Question

If you want a yellow object to turn black, what color of light will you use?

Answer 1

you can switch off light XD

Answer 2

ok so shine any colour light on it except yellow(yellow is the only color reflected the rest are absorbed)

Answer 3

And so here is a bonus question for you

if you take a yellow color object and actually try this .. the object won't look black exactly.. why do you think so?