A spotlight lens is coated so that yellow light will not be transmitted. If the light source is white, what color is the spotlight?

White = red + green + blue

yellow = red + green

white - yellow = (red + green + blue) - (red + green) = blue

Technically it would be every color because white light it just condensed colors. We just see it as white because when need something that the light can bounce of off to see the colors. For example a rainbow is just bended white light bouncing off of water vapor. Color is confusing but fell free to Dm me any questions you have.