An electromagnetic wave, going through vacuum is described by $E=E_0 sin(kx - ωt)$ Which of the following is independent of wavelength?

$\frac{k}{ω}$

Here, $kx = θ \, or \, k = \frac{\theta}{x}$

And $ ωt = \theta_0 \, or \, ω = \frac{\theta_0}{t}$

$∴ \, \frac{k}{ω} =\frac{t}{x}=\frac{1}{(x/t)}=\frac{1}{v},$ where $v$ is the velocity of electromagnetic wave, which is independent of wavelength of wave but depends upon the nature of medium of propagation of wave