Question

A linearly polarized electromagnetic wave in vacuum, is $E=3.1\cos \left[\right(1.8)z-(5.4\times {10}^6\left)t\right]\hat{i}\text{N/C}$. It is incident normally on a perfectly reflecting wall, at $z=a$. Choose the correct option.

• A. The transmitted wae will be $3.1cos\left[\right(1.8)z-(5.4\times {10}^6\left)t\right]\hat{i}\frac{N}{C}$
• B. The frequency of electromagnetic wave is $54\times {10}^4\text{Hz}$
• C. The reflected wave will be $3.1\cos \left[\right(1.8)z+(5.4\times {10}^6\left)t\right]\hat{i}\text{N/C}$
• D. The wavelength is $5.4\text{m}$

Answer 1

The correct option is C The reflected wave will be $3.1\cos \left[\right(1.8)z+(5.4\times {10}^6\left)t\right]\hat{i}\text{N/C}$

Reflected wave will have direction, opposite to incident wave.

The incident wave is, $E=3.1\cos \left[\right(1.8)z-(5.4\times {10}^6\left)t\right]\hat{i}\text{N/C}$

So, the reflected wave will be, $E=3.1\cos \left[\right(1.8)z+(5.4\times {10}^6\left)t\right]\hat{i}\text{N/C}$

Hence, $\left(D\right)$ is the correct answer.