Chapter 18.2, Problem 31SSC

To determine

The direction of the screen movement.

Answer to Problem 31SSC

In order to focus the blue light screen should be moved nearer to the lens.

Explanation of Solution

Introduction:

Convex lens is prepared from two spherical surfaces which are bent outwardly. Convex lens is also known as converging lens as it converges the ray of light incident on it and focuses it to a single point on the other side of that lens.

The size of an air particles are too small compared to that of wavelength of light and hence it scatters the light rays incident on it. It scatters the shorter wavelength colors more than other colors. Since wavelength of blue color is smaller than that of yellow, red, and orange color, it gets more scattered from air particles. Thus in order to focus the blue light, screen should be moved nearer to the lens.