Chapter 31, Problem 27A

When monochromatic light illuminates a pair of thin slits, an interference pattern is produced on a wall behind. How will the distance between the fringes of the pattern for red light differ from that for blue light?

To determine

To Explain: The difference between the distance between the fringes of the pattern for red light from that for blue light.

Explanation of Solution

Introduction:

The superposition of two or more light waves occupying the equal space can be defined as interference of light. Hence, a pattern of interference is formed within which the amplitudes of waves may be increased, decreased or completely cancel.

The wavelength for red light is longer than the wavelength for blue light. The distance between the fringes depends on the wavelength. If the wavelength is longer, then the distance between the fringes will be greater. But if the wavelength is shorter the distance between the fringes will be smaller. Hence, the distance between the fringes of the pattern for red light differs from that for blue light.

Conclusion:

Hence, the distance between the fringes is wider due to longer wavelength as compared to blue light.