Question

The electric field intensity of plane wave propagating in unknown medium is given by
$\overrightarrow{E}=E_0{e}^{-0.4\pi z}\cos (2\pi \times {10}^{5}t-0.4\pi z)\widehat{a_x}V/m$.
ldentify the medium in which the plane wave is propagating?

Answer 1

Given $\overrightarrow{E}=E_0{e}^{-0.4\pi z}\cos (2\pi \times {10}^{5}t-0.4\pi z)\widehat{a_x}$

direction of propagation : +z

attenuation constant,$\alpha =0.4\pi N/m$

phase shift constant,$\beta =0.4\pi r/m$

$\therefore \alpha =\beta =0.4\pi$

Note: When the wave is traveling in a good conductor, both attenuation constant $\alpha$ and phase shift constant$\beta$ are numerically equal.

As $\alpha$ and $\beta$ of the given wave are same $0.4\pi$ and hence the wave istraveling in a good conductor.