Question

The electric fields part of an electromagnetic wave in a medium is represented by $E_{x} = 0,$

$E_{y} = 2.5\frac{N}{C}\cos\left\lbrack \left( 2\pi \times 10^{6}\frac{rad}{m} \right)t - \left( \pi \times 10^{- 2}\frac{rad}{s} \right)x \right\rbrack E_{z} = 0,The$wave is

• A. Moving along x direction with frequency $10^{6}$Hz and wavelength 100 m
• B. Moving along x direction with frequency $10^{6}$Hz and wavelength 200m
• C. Moving along -x direction with frequency $10^{6}$Hz and wavelength 200m
• D. Moving along y direction with frequency $2\pi \times 10^{6}$Hz and wavelength 200m

Answer 1

Answer: (B)

Moving along x direction with frequency $10^{6}$Hz and wavelength 200m

Answer 2

: $E_{y} = 2.5\frac{N}{C} \times \cos\left\lbrack \left( 2\pi \times 10^{6}\frac{rad}{m} \right)t - \left( \pi \times 10^{- 2}\frac{rad}{s} \right)x \right\rbrack$

$E_{z} = 0,E_{x} = 0$

The wave is moving in the positive direction of x. This is in the form $E_{y} = E_{0}(\omega t - kx)$

$\omega = 2\pi \times 10^{6}$

$2\pi\upsilon = 2\pi \times 10^{6} \Rightarrow \upsilon = 10^{6}Hz$

$\Rightarrow \lambda = \frac{2\pi}{\pi \times 10^{- 2}} = 2 \times 10^{2} = 200m$