TABLE OF CONTENTS The phenomena of interference and diffraction establish the wave nature of light. However, they fail to throw any light on the nature of light waves. Naturally the question arises, are the light waves longitudinal or transverse, or are the vibrations linear, circular, elliptical or torsional? From the study of sound we know that a longitudinal wave has the same properties with respect to any plane through its line of propagation; while a transverse wave behaves differently in different planes. The phenomenon of polarization establishes the transverse nature of light waves as transverse waves. Before discussing the phenomenon of the polarization of light we will explain the meaning of the polarization of a wave. Now we shall discuss the simple experiment which helps in understanding polarization.
Consider a transverse wave on a string AB passes through two parallel slits S 1 and S 2 as shown in Figure 1( a). The string is attached to a fixed point at B. If the slit S 1 is parallel to the direction of the transverse vibrations, the wave passes through the slit undisturbed. Now slit S 2 is rotated 90 about AB so that its axis becomes perpendicular to slit S 1. In this case, the vibrations pass through the slit S 1 undisturbed as before but are not able to transmit through S 2 as shown in...
