Question

The electric field of an electromagnetic wave travelling through vacuum is given by the equation $E = E_{0}\sin(kx - \omega t).$ The quantity that is independent of wavelength is :

• A. $k\omega$
• B. $\frac{k}{\omega}$
• C. $k^{2}\omega$
• D. $\omega$

Answer 1

Answer: (B)

$\frac{k}{\omega}$

Answer 2

: Here, $k = \frac{2\pi}{\lambda},\omega = 2\pi\upsilon$

$\therefore\frac{k}{\omega} = \frac{2\pi/\lambda}{2\pi\upsilon} = \frac{1}{\upsilon\lambda} = \frac{1}{c}$ ($\because c = \upsilon\lambda$)

Where c is the speed of electromagnetic wave in vacuum. It is constant whose value is $3 \times 10^{8}ms^{- 1}$.