Chapter 16, Problem 61A

To determine

Whether a community that has sodium vapor streetlights should buy a dark blue police cars.

Answer to Problem 61A

Dark blue cars are not very visible under sodium vapor streetlights. Thus, if it is needed that the police cars to be visible, a community must by yellow cars.

Explanation of Solution

Introduction:

It is very well known that any objects can be seen merely in the existence of light. The light raysincident on an object get reflected off from the surface of that object and it is responsible for the visibility of that object. The color of the light reflected from an object is the actual color of that object.

It is given that the streetlights contain sodium vapor under high pressure which produces light that is mainly yellow with some red color. Yellow and red colors are gets absorbed by the blue pigment. Hence under sodium vapor streetlights one cannot see thedark blue cars. Thus, if the community needs that the police cars should be visible, they must use yellow cars. Yellow cars can reflect the yellow lights from sodium vapor streetlights and is visible to an observer.