Chapter 28, Problem 31A

To determine

The color of the emerging beam of light.

Explanation of Solution

Introduction: 

The three major colors are red, green, and blue which form different colors of light. Any pair of colors produces the new another color. 

Explanation: 

The major colors of the light are red, green, and blue. The color of the emerging beam of light depends on the stop band width of the filter. The blue part of the spectrum is relatively narrow, so only red and green are reflected if it does not transmit blue. When the blue color is not transmitted from the white-hot filament, there is enough red and green light. The combination of these colors produce yellow. So, yellow is the color emerging beam of light. 

Conclusion: 

Yellow is the color emerging beam of light in the absence of blue.