Chapter 28, Problem 28A

To determine

To Explain: The colors that appear on the screen at the point of overlapping of two beams and the color when there are two panes of glass placed in the path of white light. 

Explanation of Solution

Introduction: 

The primary colors are red, green, and blue. When they are mixed, white light is formed. The mixing of lights is just like the mixing of pigments. 

Explanation: 

The mixing of primary colors results in white color. The mixing of green and red gives the yellow light. Mixing of red and blue gives magenta and mixing blue and green results in cyan. In the first case, the white light passes through the red glass, the red light comes out and falls on the screen. Similarly, the white light falls on the green pane, the green light comes out and falls on the screen. When they overlap on the screen, yellow color is obtained on the screen. 

In the second case, there are two panes of glass.

When the single beam passes through these two panes, then all the colors will be absorbed in the panes, so no light will be transmitted.

Conclusion:

In first case the yellow color appears on the screen due to mixing of red and green and in the second case, no light will be transmitted.