Topic: Electromagnetics
A plane wave propagating in the dielectric medium has an electric field given as $E_{x}=E_{0}cos(3\times10^{10}t-100~z)$. The dielectric constant of the medium is
- A. 1.33
- B. 1.00
- C. 1.01
- D. 2.15
Answer: B. 1.00
Explanation: $E_{x}=E_{0}cos(3\times10^{10}t-100z)$. $\omega=3\times10^{10}$, $\beta=100$. $v_{\rho}=\frac{\omega}{\beta}=\frac{1}{\sqrt{\mu~\epsilon}}=\frac{c}{\sqrt{\epsilon}}$. $3\times10^{8}=\frac{3\times10^{8}}{\sqrt{\epsilon}} \Rightarrow \sqrt{\epsilon}=1 \Rightarrow \epsilon=1$.