Topic: Electromagnetics
A wave is incident from free-space onto a dielectric region of dielectric constante $\epsilon_{r}=4$. The wave impedance in the dielectric is
- A. 55.5 $\Omega$
- B. 100.5 $\Omega$
- C. 108.6 $\Omega$
- D. 188.5 $\Omega$
Answer: D. 188.5 $\Omega$
Explanation: The wave impedance in a dielectric medium is $Z = \sqrt{\frac{\mu}{\epsilon}} = \frac{\eta_0}{\sqrt{\epsilon_r}}$.
Given $\eta_0 \approx 377~\Omega$ and $\epsilon_r = 4$.
$Z = \frac{377}{\sqrt{4}} = \frac{377}{2} = 188.5~\Omega$.