The Wave Nature of Light

Abstract

As was noted in Chap. 1, light exhibits a dual nature: At times, light behaves as a particle, and at other times, as a wave. In this chapter, we will examine the properties of waves and introduce the wave nature of light .

It seems we have strong reason to conclude that light itself (including radiant heat, and other radiations if any) is an electromagnetic disturbance in the form of waves propagated through the electromagnetic field according to electromagnetic laws.

—James Clerk Maxwell

Glossary of Terms

amplitude

Maximum displacement from equilibrium in a wave.

antinode

Point of maximum amplitude due to constructive interference.

dispersion

Variation in the speed of a wave with frequency (or wavelength). The spreading of light into a spectrum of different colors.

Doppler effect

Change in the frequency of waves due to motion of the source, the observer, or both.

frequency

Number of waves per second .

hertz

Unit of frequency; equals one wave per second .

interference

Superposition of two or more waves. Constructive interference occurs when the waves are in phase and therefore combine to form a larger wave; destructive interference occurs when the waves are out of phase and partially (or fully) cancel each other.

linear superposition

The resultant displacement of two waves at a point is the sum of the displacements that the two waves would separately produce at that point.

node

Point of minimum amplitude due to destructive interference of two waves.

standing wave

An interference pattern formed by two waves of the same frequency moving in opposite directions; the pattern has alternative minima (nodes) and maxima (antinodes).

wave equation

The relationship between wave speed, frequency, and wavelength: v = fλ.

wave model of light

Light consists of electromagnetic waves.

wavelength

Distancebetween adjacent crests or adjacent troughs.