Yello light on a red object, the object appears what color?

In order to understand what happens, let's consider for a moment why

it's called a "red object" to begin with. The reason it's called "red" is that

whenever the light shining on it contains any red light, the object absorbs

light of any other colors, and only red light remains to bounce off of it toward

your eyes. Since most light contains plenty of red ... such as sunlight or the

light from an electric bulb ... the object usually looks red when you see it.

In the rare event when the light illuminating it has no red in it ... such as the

situation you describe in your question ... no light remains to bounce off of

the object to your eyes, since the object absorbs any light that's not red.

When that happens, the object appears black.