Polarized waves are transverse rather than longitudinal due to the nature of the oscillations of the electric and magnetic fields that comprise the wave.
In a transverse wave, the oscillations of the fields occur perpendicular to the direction of wave propagation. This means that the electric and magnetic fields oscillate in a plane that is perpendicular to the direction in which the wave is traveling.
On the other hand, in a longitudinal wave, the oscillations of the fields occur parallel to the direction of wave propagation. In this case, the electric and magnetic fields would oscillate in the same direction as the wave is traveling.
Electromagnetic waves, including light, consist of mutually perpendicular oscillating electric and magnetic fields. These fields are coupled and propagate through space as a wave. The orientation and behavior of these fields determine the polarization of the wave.
In a polarized transverse wave, the electric and magnetic fields oscillate in perpendicular directions to each other and to the direction of wave propagation. This arrangement is commonly referred to as transverse because the oscillations occur perpendicular to the direction of motion.
The transverse nature of polarized waves is a fundamental characteristic of electromagnetic waves. It is a consequence of the Maxwell's equations, which describe the behavior of electric and magnetic fields and their interactions. These equations predict that electromagnetic waves propagate as transverse waves, and numerous experimental observations have confirmed this behavior.
It is worth noting that longitudinal waves do exist in other physical phenomena, such as sound waves in a material medium, where the particles of the medium vibrate parallel to the direction of wave propagation. However, in the case of electromagnetic waves, their nature as transverse waves arises from the fundamental properties of the electric and magnetic fields and their interactions.