The plane wave propagating through the dielectric has the magneti

The plane wave propagating through the dielectric has the magnetic field component as

\(\vec H = 20{e^{ - \alpha x}}\cos \left( {\omega t - 0.25x} \right){\hat a_y}\;\frac{A}{m}\left( {{{\hat a}_x},\;{{\hat a}_y},\;\hat a} \right)z\;\) are unit vectors along x, y, and z-axis respectively). The polarization of the wave is in direction of:

A. <span style=" line-height: 115%; background-image: initial; background-position: initial; background-size: initial; background-repeat: initial; background-attachment: initial; background-origin: initial; background-clip: initial;">âx

B. -âz

C. \(\frac{{\left( {{{\hat a}_x} + {{\hat a}_y}} \right)}}{{\sqrt 2 }}\)

D. ây

Please scroll down to see the correct answer and solution guide.

Right Answer is: B

SOLUTION

Concept:

According to Poynting Theorem:

â_E × â_H = Direction of propagation

â_E × â_y = â_x

â_E = -â_z

Polarization of the wave is the direction of the electric field component

Application:

Given: Magnetic field component is:

\(\vec H = 20{e^{ - az}}\cos \left( {\omega t - 0.2x} \right){\hat a_y}\;A/m\;\)

The direction of propagation of the wave is â_x and the direction of the magnetic field component is â_y.

∴ Polarization of the wave is -â_z