The speed of electromagnetic waves is the same for .......

$A$ plane electromagnetic wave of frequency $20 \text{ MHz}$ travels through space along the $x$-direction. If the electric field vector at a certain point in space is $6 \text{ V m}^{-1}$,what is the magnetic field vector at that point?

The electric field of an electromagnetic wave in free space is given by $\vec E = 10 \cos (10^7 t + kx) \hat j \, V/m$,where $t$ and $x$ are in seconds and metres respectively. It can be inferred that:
$(1)$ The wavelength $\lambda$ is $188.4 \, m$.
$(2)$ The wave number $k$ is $0.33 \, rad/m$.
$(3)$ The wave amplitude is $10 \, V/m$.
$(4)$ The wave is propagating along $+x$ direction.
Which one of the following pairs of statements is correct?

An electromagnetic $(EM)$ wave is propagating in a medium with a velocity $\vec{v} = v\hat{i}$. The instantaneous oscillating electric field of this $EM$ wave is along the $+y$ axis. Then the direction of the oscillating magnetic field of the $EM$ wave will be along:

Dimension of $\frac{1}{\mu_0 \varepsilon_0}$ should be equal to

If ${\mu_r}$ is the relative permeability and $K$ is the dielectric constant of a medium,its refractive index $n$ is given by: