Question

A piece of paper appears black in sunlight. What will be its colour when seen in red light?

Answer 1

1. A piece of paper appears black in sunlight means it absorbs all colours of light and reflects none. So, when we see this piece of paper in red light, there also it absorbs all colours of light and will appear black.
2. The concept Used here is COLOUR OF AN OPAQUE OBJECT which states -When white light (or sunlight) falls on an opaque object, it reflects the light of some colours and absorbs the light of rest of the colours. The colour of an opaque object is the colour of light that it reflects and that reaches our eyes.

Hence, a piece of paper appears black in red light.