Question

A pure red object on a black background seems to disappear when illuminated with pure green light. Explain why.

Short answer

A pure red object absorbs all the green light and forms black color and due to the black background, it seems to have disappeared.

Step-by-step solution

Concept Introduction

To explain, the concept of the "true color" of an object is applied. When any object reflects the light falling on it, then the color corresponding to the wavelength of reflected light is known as the true color of the object.

Disappearance of object

In another sense, the true color of an object is defined by its absorptive and reflective characteristics of the surface, where the light falls and gets reflected. And it is also related to the relative absorption of various wavelengths of light.

Now, when a pure red object is illuminated with pure green light, the object appears to be black. This happens because the object absorbs all the green light falling on it. As the background is also black, the object now seems to disappear.

Therefore, due to the red object absorbing green light, it appears to be disappeared.