Why's a white piece of paper white in white light, red in red light, blue in blue light, & for every color?

Answer 1

White reflects the light.

Answer 2

Colour is not an intrinsic property of an object, although we have been educated since kindergarten to consider it is. The colour of an object is given by the colour of the _light_ reflected by it. The colour (or better said, colour composition) of the light reflected by an object is a combination of the colour properties if the light coming on the object and the reflective properties of the object.

A "white" object reflects all light equally, and "white" light contains all colours equally. Therefore, coloured light will be reflected "as is" by the white object, and therefore the object will appear to have the colour of the incoming light. If you use red light, there is nothing else to affect this colour, and any object will appear to be red, regardless of what colour it appears to have in daylight. But remember, to be like this, you need pure red colour, such that generated by a led or a laser diode. If you use a photographic red filter, it is still broadband, and it will contain other colours, enough for an object of another colour not to appear red (for example, a yellow object may appear orange)

As a sideline, for most of our history, the composition of light was pretty much the same , similar to daylight thermal source (sun). Since the incoming light is the same for all objects, the colour appears to be a property of the object itself.

Answer 3

White light is composed of all colors, but together, it looks white. White paper will reflect white color and "look" like white paper. Red light is composed of only red color light. The paper will reflect only red light and it will "look" like red paper. Same thing for every colors.

Answer 4

What colour we see is depends on what is reflected from the object we are seeing. As you said a white paper looks white in white light and white is formed due to combination of all the colour ( say the basics one VIBGYOR) thus the paper reflects all the colour and thus we get white in return. And when we throw red light on it as we noticed in case of white light it reflects all the colour and the same thing goes on happening with all other colours.

Answer 5

The paper is only white when it reflects white light, just like yellow paper would appear orangish when it reflects red light. White is a neutral color, so it reflects back whatever light it receives.

Answer 6

If paper is white then it reflects the incoming radiation with the same reflection coefficient for any wavelength (color). Therefore when you look at the piece of white paper you see the reflected radiation. If the radiation is green - you will see green, blue - blue and so on. Coloured paper has selective reflection coefficient. For example green paper will presumable reflect green radiation and absorb blue and red. If you look at it in red light, it will appear black (dark grey).

Answer 7

It is similar to pieces of cloth in different colors - in other words the coloring process is apparently the same!

Answer 8

white is the absence of color

Answer 9

Because it's transparent. Therfore you can see lights through it