Discussion
In a good conductor the phase relation between the tangential components of electric E and the magnetic field H is as follows :
Answer: D
In a good conductor E leads H by 45 degrees.
The ratio of the tangential electric and magnetic fields is the intrinsic impedance. For a good conductor
\[ \begin{aligned} \eta &= \sqrt{\frac{j\omega\mu}{\sigma}} \\ &= \sqrt{\frac{\omega\mu}{\sigma}}\,\angle 45^{\circ} \end{aligned} \]
because \(\sqrt{j} = e^{j\pi/4}\). Since \(E = \eta H\), the electric field is 45° ahead of the magnetic field.
E and H are in phase only in a lossless dielectric, where \(\eta\) is real. They are never 90° apart in a propagating wave; that limit would need \(\eta\) purely imaginary. 'Out of phase' (180°) does not arise either.
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