The wave length of a 100 MHz electromagnetic wave propagating through a perfect non magnetic dielectric with relative permittivity $\epsilon_r=9$ is
- A. 3 mtrs
- B. 3 cms
- C. 100 cms
- D. 10 cms
Answer: C. 100 cms
Explanation: $\lambda = \frac{v}{f} = \frac{c}{\sqrt{\epsilon_r} \cdot f} = \frac{3\times 10^8 / \sqrt{9}}{100\times 10^6} = \frac{1\times 10^8}{10^8} = 1\text{ m} = 100\text{ cm}$.